ComprehensiveZmanimCalendar.java

/*
 * Zmanim Java API
 * Copyright (C) 2004-2026 Eliyahu Hershfeld
 *
 * This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General
 * Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option)
 * any later version.
 *
 * This library is distributed in the hope that it will be useful,but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
 * details.
 * You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA,
 * or connect to: https://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
 */
package com.kosherjava.zmanim;

import java.time.Instant;
import java.time.LocalTime;
import com.kosherjava.zmanim.util.AstronomicalCalculator;
import com.kosherjava.zmanim.util.GeoLocation;
import com.kosherjava.zmanim.hebrewcalendar.JewishCalendar;

/**
 * <p>This class extends ZmanimCalendar and provides many more <em>zmanim</em> than available in the ZmanimCalendar. The basis
 * for most <em>zmanim</em> in this class are from the <em>sefer</em> <b><a href="https://hebrewbooks.org/9765">Yisroel
 * Vehazmanim</a></b> by <b><a href="https://en.wikipedia.org/wiki/Yisroel_Dovid_Harfenes">Rabbi Yisrael Dovid Harfenes</a></b>.
 * As an example of the number of different <em>zmanim</em> made available by this class, there are methods to return 18
 * different calculations for <em>alos</em> (dawn), 18 for <em>plag hamincha</em> and 29 for <em>tzais</em> available in this
 * API. The real power of this API is the ease in calculating <em>zmanim</em> that are not part of the library. The methods for
 * <em>zmanim</em> calculations not present in this class or it's superclass  {@link ZmanimCalendar} are contained in the
 * {@link AstronomicalCalendar}, the base class of the calendars in our API since they are generic methods for calculating
 * time based on degrees or time before or after {@link #getSunset() sunrise} and {@link #getSunset()
 * sunset} and are of interest for calculation beyond <em>zmanim</em> calculations. Here are some examples.
 * <p>First create the Calendar for the location you would like to calculate:
 * 
 * <pre style="background: #FEF0C9; display: inline-block;">
 * String locationName = "Lakewood, NJ";
 * double latitude = 40.0828; // Lakewood, NJ
 * double longitude = -74.222; // Lakewood, NJ
 * double elevation = 20; // optional elevation correction in Meters
 * // the String parameter in getZoneId() has to be a valid ZoneId listed in {@link java.time.ZoneId#getAvailableZoneIds()}
 * ZoneId zoneId = ZoneId.of("America/New_York");
 * GeoLocation location = new GeoLocation(locationName, latitude, longitude, elevation, zoneId);
 * ComprehensiveZmanimCalendar czc = new ComprehensiveZmanimCalendar(location);
 * // Optionally set the date or it will default to today's date
 * ZonedDateTime dateTime = ZonedDateTime.of(1969, Month.FEBRUARY.getValue(), 8, 0, 0, 0, 0, location.getZoneId());
 * czc.setZonedDateTime(dateTime);</pre>
 * <p>
 * <b>Note:</b> For locations such as Israel where the beginning and end of daylight savings time can fluctuate from
 * year to year, if your version of Java does not have an <a href=
 * "https://www.oracle.com/java/technologies/tzdata-versions.html">up to date time zone database</a>, create a
 * {@link java.util.SimpleTimeZone} with the known start and end of DST.
 * To get <em>alos</em> calculated as 14° below the horizon (as calculated in the calendars published in Montreal),
 * add {@link GEOMETRIC_ZENITH} (90) to the 14° offset to get the desired time:
 * <br><br>
 * <pre style="background: #FEF0C9; display: inline-block;">
 *  Instant alos14 = czc.getSunriseOffsetByDegrees({@link GEOMETRIC_ZENITH} + 14);</pre>
 * <p>
 * To get <em>mincha gedola</em> calculated based on the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner"
 * >Magen Avraham (MGA)</a> using a <em>shaah zmanis</em> based on the day starting
 * 16.1° below the horizon (and ending 16.1° after sunset) the following calculation can be used:
 * 
 * <pre style="background: #FEF0C9; display: inline-block;">
 * Instant minchaGedola = czc.getTimeOffset(czc.getAlos16point1Degrees(), czc.getShaahZmanis16Point1Degrees() * 6.5);</pre>
 * <p>
 * or even simpler using the included convenience methods
 * <pre style="background: #FEF0C9; display: inline-block;">
 * Instant minchaGedola = czc.getMinchaGedola(czc.getAlos16point1Degrees(), czc.getShaahZmanis16Point1Degrees());</pre>
 * <p>
 * A little more complex example would be calculating <em>zmanim</em> that rely on a <em>shaah zmanis</em> that is
 * not present in this library. While a drop more complex, it is still rather easy. An example would be to calculate
 * the <a href="https://en.wikipedia.org/wiki/Israel_Isserlein">Trumas Hadeshen</a>'s <em>alos</em> to
 * <em>tzais</em> based <em>plag hamincha</em> as calculated in the Machzikei Hadass calendar in Manchester, England.
 * A number of this calendar's <em>zmanim</em> are calculated based on a day starting at <em>alos</em> of 12° before
 * sunrise and ending at <em>tzais</em> of 7.083° after sunset. Be aware that since the <em>alos</em> and <em>tzais</em>
 * do not use identical degree-based offsets, this leads to <em>chatzos</em> being at a time other than the
 * {@link #getSunTransit() solar transit} (solar midday). To calculate this <em>zman</em>, use the following steps. Note
 * that <em>plag hamincha</em> is 10.75 hours after the start of the day, and the following steps are all that it takes.
 * <br>
 * <pre style="background: #FEF0C9; display: inline-block;">
 * Instant plag = czc.getPlagHamincha(czc.getSunriseOffsetByDegrees({@link GEOMETRIC_ZENITH} + 12),
 * 				czc.getSunsetOffsetByDegrees({@link GEOMETRIC_ZENITH} + ZENITH_7_POINT_083));</pre>
 * <p>
 * Something a drop more challenging, but still simple, would be calculating a <em>zman</em> using the same "complex"
 * offset day used in the above-mentioned Manchester calendar, but for a <em>shaos zmaniyos</em> based <em>zman</em> not
 * supported by this library, such as calculating the point that one should be <em>makpid</em>
 * not to eat on <em>erev Shabbos</em> or <em>erev Yom Tov</em>. This is 9 <em>shaos zmaniyos</em> into the day.
 * <ol>
 * 	<li>Calculate the <em>shaah zmanis</em> in milliseconds for this day</li>
 * 	<li>Add 9 of these <em>shaos zmaniyos</em> to <em>alos</em> starting at 12°</li>
 * </ol>
 * <br>
 * <pre style="background: #FEF0C9; display: inline-block;">
 * long shaahZmanis = czc.getTemporalHour(czc.getSunriseOffsetByDegrees({@link GEOMETRIC_ZENITH} + 12),
 * 						czc.getSunsetOffsetByDegrees({@link GEOMETRIC_ZENITH} + ZENITH_7_POINT_083));
 * Instant sofZmanAchila = getTimeOffset(czc.getSunriseOffsetByDegrees({@link GEOMETRIC_ZENITH} + 12),
 * 					shaahZmanis * 9);</pre>
 * <p>
 * Calculating this <em>sof zman achila</em> according to the <a href="https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a>
 * is simplicity itself.
 * <pre style="background: #FEF0C9; display: inline-block;">
 * Instant sofZmanAchila = czc.getTimeOffset(czc.getSunrise(), czc.getShaahZmanisGRA() * 9);</pre>
 * 
 * <h2>See documentation from the {@link ZmanimCalendar} parent class</h2>
 * 
 * @author &copy; Eliyahu Hershfeld 2004 - 2026
 */
public class ComprehensiveZmanimCalendar extends ZmanimCalendar {

	/**
	 * The zenith of 3.7° below {@link GEOMETRIC_ZENITH geometric zenith} (90°).
	 * @see #getTzaisGeonim3Point7Degrees()
	 */
	protected static final double ZENITH_3_POINT_7 = GEOMETRIC_ZENITH + 3.7;

	/**
	 * The zenith of 3.8° below {@link GEOMETRIC_ZENITH geometric zenith} (90°).
	 * @see #getTzaisGeonim3Point8Degrees()
	 */
	protected static final double ZENITH_3_POINT_8 = GEOMETRIC_ZENITH + 3.8;

	/**
	 * The zenith of 5.95° below {@link GEOMETRIC_ZENITH geometric zenith} (90°).
	 * @see #getTzaisGeonim5Point95Degrees()
	 */
	protected static final double ZENITH_5_POINT_95 = GEOMETRIC_ZENITH + 5.95;

	/**
	 * The zenith of 7.083° below {@link GEOMETRIC_ZENITH geometric zenith} (90°). This is often referred to as
	 * 7°5' (7° and 5 minutes).
	 * 
	 * @see #getTzaisGeonim7Point083Degrees()
	 * @see #getBainHashmashosRT13Point5MinutesBefore7Point083Degrees()
	 */
	protected static final double ZENITH_7_POINT_083 = GEOMETRIC_ZENITH + 7 + (5.0 / 60);

	/**
	 * The zenith of 10.2° below {@link GEOMETRIC_ZENITH geometric zenith} (90°).
	 * @see #getMisheyakir10Point2Degrees()
	 */
	protected static final double ZENITH_10_POINT_2 = GEOMETRIC_ZENITH + 10.2;

	/**
	 * The zenith of 11° below {@link GEOMETRIC_ZENITH geometric zenith} (90°).
	 * @see #getMisheyakir11Degrees()
	 */
	protected static final double ZENITH_11_DEGREES = GEOMETRIC_ZENITH + 11;

	/**
	 * The zenith of 11.5° below {@link GEOMETRIC_ZENITH geometric zenith} (90°).
	 * @see #getMisheyakir11Point5Degrees()
	 */
	protected static final double ZENITH_11_POINT_5 = GEOMETRIC_ZENITH + 11.5;
	
	/**
	 * The zenith of 12.85° below {@link GEOMETRIC_ZENITH geometric zenith} (90°).
	 * @see #getMisheyakir12Point85Degrees()
	 */
	protected static final double ZENITH_12_POINT_85 = GEOMETRIC_ZENITH + 12.85;

	/**
	 * The zenith of 13.24° below {@link GEOMETRIC_ZENITH geometric zenith} (90°).
	 * @see #getBainHashmashosRT13Point24Degrees
	 */
	protected static final double ZENITH_13_POINT_24 = GEOMETRIC_ZENITH + 13.24;
	
	/**
	 * The zenith of 19° below {@link GEOMETRIC_ZENITH geometric zenith} (90°).
	 * @see #getAlos19Degrees()
	 * @see ZENITH_19_POINT_8
	 */
	protected static final double ZENITH_19_DEGREES = GEOMETRIC_ZENITH + 19;

	/**
	 * The zenith of 19.8° below {@link GEOMETRIC_ZENITH geometric zenith} (90°).
	 * @see #getTzais19Point8Degrees()
	 * @see #getAlos19Point8Degrees()
	 * @see ZENITH_19_DEGREES
	 */
	protected static final double ZENITH_19_POINT_8 = GEOMETRIC_ZENITH + 19.8;

	/**
	 * The zenith of 26° below {@link GEOMETRIC_ZENITH geometric zenith} (90°).
	 * @see #getAlos26Degrees()
	 * @see #getTzais26Degrees()
	 * @see #getAlos120Minutes()
	 * @see #getTzais120Minutes()
	 */
	protected static final double ZENITH_26_DEGREES = GEOMETRIC_ZENITH + 26.0;

	/**
	 * The zenith of 4.42° below {@link GEOMETRIC_ZENITH geometric zenith} (90°).
	 * @see #getTzaisGeonim4Point42Degrees()
	 */
	protected static final double ZENITH_4_POINT_42 = GEOMETRIC_ZENITH + 4.42;

	/**
	 * The zenith of 4.66° below {@link GEOMETRIC_ZENITH geometric zenith} (90°).
	 * @see #getTzaisGeonim4Point66Degrees()
	 */
	protected static final double ZENITH_4_POINT_66 = GEOMETRIC_ZENITH + 4.66;

	/**
	 * The zenith of 4.8° below {@link GEOMETRIC_ZENITH geometric zenith} (90°).
	 * @see #getTzaisGeonim4Point8Degrees()
	 */
	protected static final double ZENITH_4_POINT_8 = GEOMETRIC_ZENITH + 4.8;

	/**
	 * The zenith of 16.9° below geometric zenith (90°).
	 *
	 * @see #getAlosBaalHatanya()
	 */
	protected static final double ZENITH_16_POINT_9 = GEOMETRIC_ZENITH + 16.9;

	/**
	 * The zenith of 6° below {@link GEOMETRIC_ZENITH geometric zenith} (90°).
	 * @see #getTzaisBaalHatanya()
	 */
	protected static final double ZENITH_6_DEGREES = GEOMETRIC_ZENITH + 6;

	/**
	 * The zenith of 6.45° below {@link GEOMETRIC_ZENITH geometric zenith} (90°).
	 * @see #getTzaisGeonim6Point45Degrees()
	 */
	protected static final double ZENITH_6_POINT_45 = GEOMETRIC_ZENITH + 6.45;
	
	/**
	 * The zenith of 7.65° below {@link GEOMETRIC_ZENITH geometric zenith} (90°).
	 * @see #getMisheyakir7Point65Degrees()
	 */
	protected static final double ZENITH_7_POINT_65 = GEOMETRIC_ZENITH + 7.65;
	
	/**
	 * The zenith of 7.67° below {@link GEOMETRIC_ZENITH geometric zenith} (90°).
	 * @see #getTzaisGeonim7Point67Degrees()
	 */
	protected static final double ZENITH_7_POINT_67 = GEOMETRIC_ZENITH + 7.67;
	
	/**
	 * The zenith of 9.3° below {@link GEOMETRIC_ZENITH geometric zenith} (90°).
	 * @see #getTzaisGeonim9Point3Degrees()
	 */
	protected static final double ZENITH_9_POINT_3 = GEOMETRIC_ZENITH + 9.3;
	
	/**
	 * The zenith of 9.5° below {@link GEOMETRIC_ZENITH geometric zenith} (90°).
	 * @see #getMisheyakir9Point5Degrees()
	 */
	protected static final double ZENITH_9_POINT_5 = GEOMETRIC_ZENITH + 9.5;
	
	/**
	 * The zenith of 9.75° below {@link GEOMETRIC_ZENITH geometric zenith} (90°). This calculation is used for
	 * calculating <em>alos</em> (dawn) and <em>tzais</em> (nightfall) according to some opinions.
	 * 
	 * @see #getTzaisGeonim9Point75Degrees()
	 */
	protected static final double ZENITH_9_POINT_75 = GEOMETRIC_ZENITH + 9.75;
	
	/**
	 * The zenith of 2.1° <b>above</b> {@link GEOMETRIC_ZENITH geometric zenith} (90°). This calculation is used for
	 * calculating the start of <em>bain hashmashos</em> (twilight) of 13.5 minutes before sunset converted to degrees
	 * according to the Yereim. As is traditional with degrees below the horizon, this is calculated without refraction
	 * and from the center of the sun. It would be 0.833° less without this.
	 * 
	 * @see #getBainHashmashosYereim2Point1Degrees()
	 */
	protected static final double ZENITH_MINUS_2_POINT_1 = GEOMETRIC_ZENITH - 2.1;
	
	/**
	 * The zenith of 2.8° above {@link GEOMETRIC_ZENITH geometric zenith} (90°). This calculation is used for
	 * calculating the start of <em>bain hashmashos</em> (twilight) of 16.875 minutes before sunset converted to degrees
	 * according to the Yereim. As is traditional with degrees below the horizon, this is calculated without refraction
	 * and from the center of the sun. It would be 0.833° less without this.
	 * 
	 * @see #getBainHashmashosYereim2Point8Degrees()
	 */
	protected static final double ZENITH_MINUS_2_POINT_8 = GEOMETRIC_ZENITH - 2.8;
	
	/**
	 * The zenith of 3.05° above {@link GEOMETRIC_ZENITH geometric zenith} (90°). This calculation is used for
	 * calculating the start of <em>bain hashmashos</em> (twilight) of 18 minutes before sunset converted to degrees
	 * according to the Yereim. As is traditional with degrees below the horizon, this is calculated without refraction
	 * and from the center of the sun. It would be 0.833° less without this.
	 * 
	 * @see #getBainHashmashosYereim3Point05Degrees()
	 */
	protected static final double ZENITH_MINUS_3_POINT_05 = GEOMETRIC_ZENITH - 3.05;

	/**
	 * The offset in minutes (defaults to 40) after sunset used for <em>tzeit</em> based on calculations of
	 * <em>Chacham</em> Yosef Harari-Raful of Yeshivat Ateret Torah.
	 * @see #getTzaisAteretTorah()
	 * @see #getAteretTorahSunsetOffset()
	 * @see #setAteretTorahSunsetOffset(double)
	 */
	private double ateretTorahSunsetOffset = 40;

	/**
	 * A constructor that takes a {@link GeoLocation} as a parameter.
	 * 
	 * @param location
	 *            the location
	 * 
	 * @see ZmanimCalendar#ZmanimCalendar(GeoLocation)
	 */
	public ComprehensiveZmanimCalendar(GeoLocation location) {
		super(location);
	}

	/**
	 * Default constructor will set a default {@link GeoLocation#GeoLocation()}, a default
	 * {@link AstronomicalCalculator#getDefault() AstronomicalCalculator} and default the calendar to the current date.
	 * 
	 * @see AstronomicalCalendar#AstronomicalCalendar()
	 * @see ComprehensiveZmanimCalendar(GeoLocation)
	 */
	public ComprehensiveZmanimCalendar() {
		super();
	}

	/**
	 * Method to return a <em>shaah zmanis</em> (temporal hour) calculated using a 19.8° dip. This calculation
	 * divides the day based on the opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen
	 * Avraham (MGA)</a> that the day runs from dawn to dusk. Dawn for this calculation is when the sun is 19.8°
	 * below the eastern geometric horizon before sunrise. Dusk for this is when the sun is 19.8° below the western
	 * geometric horizon after sunset. This day is split into 12 equal parts with each part being a <em>shaah zmanis</em>.
	 * 
	 * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
	 *         such as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
	 *         where the sun may not reach low enough below the horizon for this calculation, a {@link Long#MIN_VALUE}
	 *         will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 */
	public long getShaahZmanis19Point8Degrees() {
		return getTemporalHour(getAlos19Point8Degrees(), getTzais19Point8Degrees());
	}

	/**
	 * Method to return a <em>shaah zmanis</em> (temporal hour) calculated using a 18° dip. This calculation divides
	 * the day based on the opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham
	 * (MGA)</a> that the day runs from dawn to dusk. Dawn for this calculation is when the sun is 18° below the
	 * eastern geometric horizon before sunrise. Dusk for this is when the sun is 18° below the western geometric
	 * horizon after sunset. This day is split into 12 equal parts with each part being a <em>shaah zmanis</em>.
	 * 
	 * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
	 *         such as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
	 *         where the sun may not reach low enough below the horizon for this calculation, a {@link Long#MIN_VALUE}
	 *         will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 */
	public long getShaahZmanis18Degrees() {
		return getTemporalHour(getAlos18Degrees(), getTzais18Degrees());
	}

	/**
	 * Method to return a <em>shaah zmanis</em> (temporal hour) calculated using a dip of 26°. This calculation
	 * divides the day based on the opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen
	 * Avraham (MGA)</a> that the day runs from dawn to dusk. Dawn for this calculation is when the sun is
	 * {@link #getAlos26Degrees() 26°} below the eastern geometric horizon before sunrise. Dusk for this is when
	 * the sun is {@link #getTzais26Degrees() 26°} below the western geometric horizon after sunset. This day is
	 * split into 12 equal parts with each part being a <em>shaah zmanis</em>. Since <em>zmanim</em> that use this
	 * method are extremely late or early and at a point when the sky is a long time past the 18° point where the
	 * darkest point is reached, <em>zmanim</em> that use this should only be used <em>lechumra</em>, such as
	 * delaying the start of nighttime <em>mitzvos</em>.
	 * 
	 * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
	 *         such as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
	 *         where the sun may not reach low enough below the horizon for this calculation, a {@link Long#MIN_VALUE}
	 *         will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis120Minutes()
	 */
	public long getShaahZmanis26Degrees() {
		return getTemporalHour(getAlos26Degrees(), getTzais26Degrees());
	}

	/**
	 * Method to return a <em>shaah zmanis</em> (temporal hour) calculated using a dip of 16.1°. This calculation
	 * divides the day based on the opinion that the day runs from dawn to dusk. Dawn for this calculation is when the
	 * sun is 16.1° below the eastern geometric horizon before sunrise and dusk is when the sun is 16.1° below
	 * the western geometric horizon after sunset. This day is split into 12 equal parts with each part being a
	 * <em>shaah zmanis</em>.
	 * 
	 * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
	 *         such as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
	 *         where the sun may not reach low enough below the horizon for this calculation, a {@link Long#MIN_VALUE}
	 *         will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getAlos16Point1Degrees()
	 * @see #getTzais16Point1Degrees()
	 * @see #getSofZmanShmaMGA16Point1Degrees()
	 * @see #getSofZmanTfilaMGA16Point1Degrees()
	 * @see #getMinchaGedola16Point1Degrees()
	 * @see #getMinchaKetana16Point1Degrees()
	 * @see #getPlagHamincha16Point1Degrees()
	 */

	public long getShaahZmanis16Point1Degrees() {
		return getTemporalHour(getAlos16Point1Degrees(), getTzais16Point1Degrees());
	}

	/**
	 * Method to return a <em>shaah zmanis</em> (solar hour) according to the opinion of the <a href=
	 * "https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a>. This calculation
	 * divides the day based on the opinion of the MGA that the day runs from dawn to dusk. Dawn for this calculation is
	 * 60 minutes before sunrise and dusk is 60 minutes after sunset. This day is split into 12 equal parts with each
	 * part being a <em>shaah zmanis</em>. Alternate methods of calculating a <em>shaah zmanis</em> are available in the
	 * subclass {@link ComprehensiveZmanimCalendar}.
	 * 
	 * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
	 *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
	 *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getAlos60Minutes()
	 * @see #getTzais60Minutes()
	 * @see #getPlagHamincha60Minutes()
	 */
	public long getShaahZmanis60Minutes() {
		return getTemporalHour(getAlos60Minutes(), getTzais60Minutes());
	}

	/**
	 * Method to return a <em>shaah zmanis</em> (temporal hour) according to the opinion of the <a href=
	 * "https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being
	 * {@link #getAlos72Zmanis() 72} minutes <em>zmaniyos</em> before {@link #getSunset() sunrise}. This calculation
	 * divides the day based on the opinion of the MGA that the day runs from dawn to dusk. Dawn for this calculation
	 * is 72 minutes <em>zmaniyos</em> before sunrise and dusk is 72 minutes <em>zmaniyos</em> after sunset. This day
	 * is split into 12 equal parts with each part being a <em>shaah zmanis</em>. This is identical to 1/10th of the day
	 * from {@link #getSunset() sunrise} to {@link #getSunset() sunset}.
	 * 
	 * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
	 *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
	 *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getAlos72Zmanis()
	 * @see #getTzais72Zmanis()
	 */
	public long getShaahZmanis72MinutesZmanis() {
		return getTemporalHour(getAlos72Zmanis(), getTzais72Zmanis());
	}

	/**
	 * Method to return a <em>shaah zmanis</em> (temporal hour) calculated using a dip of 90 minutes. This calculation
	 * divides the day based on the opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen
	 * Avraham (MGA)</a> that the day runs from dawn to dusk. Dawn for this calculation is 90 minutes before sunrise
	 * and dusk is 90 minutes after sunset. This day is split into 12 equal parts with each part being a <em>shaah zmanis</em>.
	 * 
	 * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
	 *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
	 *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 */
	public long getShaahZmanis90Minutes() {
		return getTemporalHour(getAlos90Minutes(), getTzais90Minutes());
	}

	/**
	 * Method to return a <em>shaah zmanis</em> (temporal hour) according to the opinion of the <a href=
	 * "https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
	 * #getAlos90Zmanis() 90} minutes <em>zmaniyos</em> before {@link #getSunset() sunrise}. This calculation divides
	 * the day based on the opinion of the MGA that the day runs from dawn to dusk. Dawn for this calculation is 90 minutes
	 * <em>zmaniyos</em> before sunrise and dusk is 90 minutes <em>zmaniyos</em> after sunset. This day is split into 12 equal
	 * parts with each part being a <em>shaah zmanis</em>. This is 1/8th of the day from {@link #getSunset() sunrise}
	 * to {@link #getSunset() sunset}.
	 * 
	 * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
	 *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
	 *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getAlos90Zmanis()
	 * @see #getTzais90Zmanis()
	 */
	public long getShaahZmanis90MinutesZmanis() {
		return getTemporalHour(getAlos90Zmanis(), getTzais90Zmanis());
	}

	/**
	 * Method to return a <em>shaah zmanis</em> (temporal hour) according to the opinion of the <a href=
	 * "https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
	 * #getAlos96Zmanis() 96} minutes <em>zmaniyos</em> before {@link #getSunset() sunrise}. This calculation divides
	 * the day based on the opinion of the MGA that the day runs from dawn to dusk. Dawn for this calculation is 96 minutes
	 * <em>zmaniyos</em> before sunrise and dusk is 96 minutes <em>zmaniyos</em> after sunset. This day is split into 12 equal
	 * parts with each part being a <em>shaah zmanis</em>. This is identical to 1/7.5th of the day from {@link
	 * #getSunset() sunrise} to {@link #getSunset() sunset}.
	 * 
	 * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
	 *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
	 *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getAlos96Zmanis()
	 * @see #getTzais96Zmanis()
	 */
	public long getShaahZmanis96MinutesZmanis() {
		return getTemporalHour(getAlos96Zmanis(), getTzais96Zmanis());
	}

	/**
	 * Method to return a <em>shaah zmanis</em> (temporal hour) according to the opinion of the
	 * <em>Chacham</em> Yosef Harari-Raful of Yeshivat Ateret Torah calculated with <em>alos</em> being 1/10th
	 * of sunrise to sunset day, or {@link #getAlos72Zmanis() 72} minutes <em>zmaniyos</em> of such a day before
	 * {@link #getSunset() sunrise}, and <em>tzais</em> is usually calculated as {@link #getTzaisAteretTorah() 40
	 * minutes} (configurable to any offset via {@link #setAteretTorahSunsetOffset(double)}) after {@link #getSunset()
	 * sunset}. This day is split into 12 equal parts with each part being a <em>shaah zmanis</em>. Note that with this
	 * system, <em>chatzos</em> (midday) will not be the point that the sun is {@link #getSunTransit() halfway across
	 * the sky}.
	 * 
	 * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
	 *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
	 *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getAlos72Zmanis()
	 * @see #getTzaisAteretTorah()
	 * @see #getAteretTorahSunsetOffset()
	 * @see #setAteretTorahSunsetOffset(double)
	 */
	public long getShaahZmanisAteretTorah() {
		return getTemporalHour(getAlos72Zmanis(), getTzaisAteretTorah());
	}
	
	/**
	 * Method to return a <em>shaah zmanis</em> (temporal hour) used by some <em>zmanim</em> according to the opinion of
	 * <a href="https://en.wikipedia.org/wiki/Yaakov_Moshe_Hillel">Rabbi Yaakov Moshe Hillel</a> as published in the
	 * <em>luach</em> of the Bais Horaah of Yeshivat Chevrat Ahavat Shalom that is based on a day starting 72 minutes before
	 * sunrise in degrees {@link #getAlos16Point1Degrees() <em>alos</em> 16.1°} and ending 14 minutes after sunset in
	 * degrees {@link #getTzaisGeonim3Point8Degrees() <em>tzais</em> 3.8°}. This day is split into 12 equal parts with
	 * each part being a <em>shaah zmanis</em>. Note that with this system, <em>chatzos</em> (midday) will not be the point
	 * that the sun is {@link #getSunTransit() halfway across the sky}. These <em>shaos zmaniyos</em> are used for <em>Mincha
	 * Ketana</em> and <em>Plag Hamincha</em>. The 14 minutes are based on 3/4 of an 18 minute <a href=
	 * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement" >mil</a>, with half a minute added for
	 * Rav Yosi.
	 * 
	 * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
	 *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
	 *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getMinchaKetanaAhavatShalom()
	 * @see #getPlagAhavatShalom()
	 */
	public long getShaahZmanisAlos16Point1ToTzais3Point8() {
		return getTemporalHour(getAlos16Point1Degrees(), getTzaisGeonim3Point8Degrees());
	}
	
	/**
	 * Method to return a <em>shaah zmanis</em> (temporal hour) used by some <em>zmanim</em> according to the opinion of
	 * <a href="https://en.wikipedia.org/wiki/Yaakov_Moshe_Hillel">Rabbi Yaakov Moshe Hillel</a> as published in the
	 * <em>luach</em> of the Bais Horaah of Yeshivat Chevrat Ahavat Shalom that is based on a day starting 72 minutes before
	 * sunrise in degrees {@link #getAlos16Point1Degrees() <em>alos</em> 16.1°} and ending 13.5 minutes after sunset in
	 * degrees {@link #getTzaisGeonim3Point7Degrees() <em>tzais</em> 3.7°}. This day is split into 12 equal parts with
	 * each part being a <em>shaah zmanis</em>. Note that with this system, <em>chatzos</em> (midday) will not be the point
	 * that the sun is {@link #getSunTransit() halfway across the sky}. These <em>shaos zmaniyos</em> are used for <em>Mincha
	 * Gedola</em> calculation.
	 * 
	 * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
	 *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
	 *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getMinchaGedolaAhavatShalom()
	 */
	public long getShaahZmanisAlos16Point1ToTzais3Point7() {
		return getTemporalHour(getAlos16Point1Degrees(), getTzaisGeonim3Point7Degrees());
	}

	/**
	 * Method to return a <em>shaah zmanis</em> (temporal hour) calculated using a dip of 96 minutes. This calculation
	 * divides the day based on the opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen
	 * Avraham (MGA)</a> that the day runs from dawn to dusk. Dawn for this calculation is 96 minutes before sunrise
	 * and dusk is 96 minutes after sunset. This day is split into 12 equal parts with each part being a <em>shaah
	 * zmanis</em>.
	 * 
	 * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
	 *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
	 *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 */
	public long getShaahZmanis96Minutes() {
		return getTemporalHour(getAlos96Minutes(), getTzais96Minutes());
	}

	/**
	 * Method to return a <em>shaah zmanis</em> (temporal hour) calculated using a dip of 120 minutes. This calculation
	 * divides the day based on the opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen
	 * Avraham (MGA)</a> that the day runs from dawn to dusk. Dawn for this calculation is 120 minutes before sunrise and
	 * dusk is 120 minutes after sunset. This day is split into 12 equal parts with each part being a <em>shaah zmanis</em>.
	 * Since <em>zmanim</em> that use this method are extremely late or early and at a point when the sky is a long time
	 * past the 18° point where the darkest point is reached, <em>zmanim</em> that use this should only be used
	 * <em>lechumra</em> only, such as delaying the start of nighttime <em>mitzvos</em>.
	 * 
	 * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
	 *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
	 *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis26Degrees()
	 */
	public long getShaahZmanis120Minutes() {
		return getTemporalHour(getAlos120Minutes(), getTzais120Minutes());
	}

	/**
	 * Method to return a <em>shaah zmanis</em> (temporal hour) according to the opinion of the <a href=
	 * "https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
	 * #getAlos120Zmanis() 120} minutes <em>zmaniyos</em> before {@link #getSunset() sunrise}. This calculation divides
	 * the day based on the opinion of the MGA that the day runs from dawn to dusk. Dawn for this calculation is 120 minutes
	 * <em>zmaniyos</em> before sunrise and dusk is 120 minutes <em>zmaniyos</em> after sunset. This day is split into 12 equal
	 * parts with each part being a <em>shaah zmanis</em>. This is identical to 1/6th of the day from {@link
	 * #getSunset() sunrise} to {@link #getSunset() sunset}. Since <em>zmanim</em> that use this method are
	 * extremely late or early and at a point when the sky is a long time past the 18° point where the darkest point is reached,
	 * <em>zmanim</em> that use this should only be used <em>lechumra</em> such as delaying the start of nighttime <em>mitzvos</em>.
	 * 
	 * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em>. If the calculation can't be computed
	 *         such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one
	 *         where it does not set, a {@link Long#MIN_VALUE} will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getAlos120Zmanis()
	 * @see #getTzais120Zmanis()
	 */
	public long getShaahZmanis120MinutesZmanis() {
		return getTemporalHour(getAlos120Zmanis(), getTzais120Zmanis());
	}

	/**
	 * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em> based on sunrise
	 * being 120 minutes <em>zmaniyos</em> or 1/6th of the day before sunrise. This is calculated as 10.75 hours after
	 * {@link #getAlos120Zmanis() dawn}. The formula used is 10.75 * {@link #getShaahZmanis120MinutesZmanis()} after
	 * {@link #getAlos120Zmanis() dawn}. Since the <em>zman</em> based on an extremely early <em>alos</em> and a very
	 * late <em>tzais</em>, it should only be used <em>lechumra</em>.
	 * 
	 * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
	 *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
	 *         current plan to remove this method from the API, and this deprecation is intended to alert developers
	 *         of the danger of using it.
	 * 
	 * @return the <code>Instant</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
	 *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
	 *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getShaahZmanis120MinutesZmanis()
	 * @see #getAlos120Minutes()
	 * @see #getTzais120Minutes()
	 * @see #getPlagHamincha26Degrees()
	 * @see #getPlagHamincha120Minutes()
	 */
	@Deprecated (forRemoval=false)
	public Instant getPlagHamincha120MinutesZmanis() {
		return getPlagHamincha(getAlos120Zmanis(), getTzais120Zmanis(), true);
	}

	/**
	 * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em> according to the
	 * Magen Avraham with the day starting 120 minutes before sunrise and ending 120 minutes after sunset. This is
	 * calculated as 10.75 hours after {@link #getAlos120Minutes() dawn 120 minutes}. The formula used is 10.75 {@link
	 * #getShaahZmanis120Minutes()} after {@link #getAlos120Minutes()}. Since the <em>zman</em> based on an extremely early
	 * <em>alos</em> and a very late <em>tzais</em>, it should only be used <em>lechumra</em>.
	 * 
	 * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
	 *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
	 *         current plan to remove this method from the API, and this deprecation is intended to alert developers
	 *         of the danger of using it.
	 * 
	 * @return the <code>Instant</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
	 *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
	 *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getShaahZmanis120Minutes()
	 * @see #getPlagHamincha26Degrees()
	 */
	@Deprecated (forRemoval=false)
	public Instant getPlagHamincha120Minutes() {
		return getPlagHamincha(getAlos120Minutes(), getTzais120Minutes(), true);
	}

	/**
	 * Method to return <em>alos</em> (dawn) calculated as 60 minutes before {@link #getSunset() sunrise} or
	 * {@link #getSeaLevelSunrise() sea level sunrise} (depending on the {@link #isUseElevation()} setting). This is the
	 * time to walk the distance of 4 <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement"
	 * >mil</a> at 15 minutes a mil. This seems to be the opinion of the <a href="https://en.wikipedia.org/wiki/Yair_Bacharach"
	 * >Chavas Yair</a> in the Mekor Chaim, Orach Chaim Ch. 90, though  the Mekor Chaim in Ch. 58 and in the <a href=
	 * "https://hebrewbooks.org/pdfpager.aspx?req=45193&pgnum=214">Chut Hashani Ch. 97</a> states that a person walks 3 and a
	 * 1/3 mil in an hour, or an 18-minute mil. Also see the <a href=
	 * "https://he.wikipedia.org/wiki/%D7%9E%D7%9C%D7%9B%D7%99%D7%90%D7%9C_%D7%A6%D7%91%D7%99_%D7%98%D7%A0%D7%A0%D7%91%D7%95%D7%99%D7%9D"
	 * >Divrei Malkiel</a> <a href="https://hebrewbooks.org/pdfpager.aspx?req=803&pgnum=33">Vol. 4, Ch. 20, page 34</a>) who mentions the
	 * 15 minute mil <em>lechumra</em> by baking matzos. Also see the <a href="https://en.wikipedia.org/wiki/Joseph_Colon_Trabotto"
	 * >Maharik</a> <a href="https://hebrewbooks.org/pdfpager.aspx?req=1142&pgnum=216">Ch. 173</a> where the questioner quoting
	 * the <a href="https://en.wikipedia.org/wiki/Eliezer_ben_Nathan">Ra'avan</a> is of the opinion that the time to walk a mil is
	 * 15 minutes (5 mil in a little over an hour). There are many who believe that there is a <em>ta'us sofer</em> (scribe's
	 * error) in the Ra'avan, and it should 4 mil in a little over an hour, or an 18-minute mil. Time based offset calculations are
	 * based on the opinion of the <em><a href="https://en.wikipedia.org/wiki/Rishonim">Rishonim</a></em> who stated that the time
	 * of the <em>neshef</em> (time between dawn and sunrise) does not vary by the time of year or location but purely depends on
	 * the time it takes to walk the distance of 4* mil. {@link #getTzaisGeonim9Point75Degrees()} is a related <em>zman</em> that
	 * is a degree-based calculation based on 60 minutes.
	 * 
	 * @return the <code>Instant</code> representing the time. If the calculation can't be computed such as in the Arctic
	 *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
	 *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}.
	 *         documentation.
	 *
	 * @see #getTzais60Minutes()
	 * @see #getPlagHamincha60Minutes()
	 * @see #getShaahZmanis60Minutes()
	 */
	public Instant getAlos60Minutes() {
		return getTimeOffset(getSunriseBasedOnElevationSetting(), -60 * MINUTE_MILLIS);
	}

	/**
	 * Method to return <em>alos</em> (dawn) calculated using 72 minutes <em>zmaniyos</em> or 1/10th of the day before
	 * sunrise. This is based on an 18-minute <a href=
	 * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> so the time for 4 mil is
	 * 72 minutes which is 1/10th of a day (12 * 60 = 720) based on the day being from {@link #getSeaLevelSunrise() sea
	 * level sunrise} to {@link #getSeaLevelSunset() sea level sunset} or {@link #getSunset() sunrise} to {@link
	 * #getSunset() sunset} (depending on the {@link #isUseElevation()} setting). The actual calculation is {@link
	 * #getSunriseBasedOnElevationSetting()} - ({@link #getShaahZmanisGRA()} * 1.2). This calculation is used in the calendars
	 * published by the <a href="https://en.wikipedia.org/wiki/Central_Rabbinical_Congress">Hisachdus Harabanim D'Artzos Habris
	 * Ve'Canada</a>.
	 * 
	 * @return the <code>Instant</code> representing the time. If the calculation can't be computed such as in the Arctic
	 *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
	 *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
	 *         documentation.
	 * @see #getShaahZmanisGRA()
	 */
	public Instant getAlos72Zmanis() {
		return getZmanisBasedOffset(-1.2);
	}

	/**
	 * Method to return <em>alos</em> (dawn) calculated using 96 minutes before {@link #getSunset() sunrise} or
	 * {@link #getSeaLevelSunrise() sea level sunrise} (depending on the {@link #isUseElevation()} setting) that is based
	 * on the time to walk the distance of 4 <a href=
	 * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> at 24 minutes a mil.
	 * Time based offset calculations for <em>alos</em> are based on the opinion of the <em><a href=
	 * "https://en.wikipedia.org/wiki/Rishonim">Rishonim</a></em> who stated that the time of the <em>Neshef</em> (time between
	 * dawn and sunrise) does not vary by the time of year or location but purely depends on the time it takes to walk the
	 * distance of 4 mil.
	 * 
	 * @return the <code>Instant</code> representing the time. If the calculation can't be computed such as in the Arctic
	 *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
	 *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
	 *         documentation.
	 */
	public Instant getAlos96Minutes() {
		return getTimeOffset(getSunriseBasedOnElevationSetting(), -96 * MINUTE_MILLIS);
	}

	/**
	 * Method to return <em>alos</em> (dawn) calculated using 90 minutes <em>zmaniyos</em> or 1/8th of the day before
	 * {@link #getSunset() sunrise} or {@link #getSeaLevelSunrise() sea level sunrise} (depending on the {@link
	 * #isUseElevation()} setting). This is based on a 22.5-minute <a href=
	 * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> so the time for 4 mil is 90 minutes
	 * which is 1/8th of a day (12 * 60) / 8 = 90. The day is calculated from {@link #getSeaLevelSunrise() sea level sunrise}
	 * to {@link #getSeaLevelSunset() sea level sunset} or {@link #getSunset() sunrise} to {@link
	 * #getSunset() sunset} (depending on the {@link #isUseElevation()}. The actual calculation used is
	 * {@link #getSunriseBasedOnElevationSetting()} - ({@link #getShaahZmanisGRA()} * 1.5).
	 * 
	 * @return the <code>Instant</code> representing the time. If the calculation can't be computed such as in the Arctic
	 *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
	 *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
	 *         documentation.
	 * @see #getShaahZmanisGRA()
	 */
	public Instant getAlos90Zmanis() {
		return getZmanisBasedOffset(-1.5);
	}

	/**
	 * This method returns <em>alos</em> (dawn) calculated using 96 minutes <em>zmaniyos</em> or 1/7.5th of the day before
	 * {@link #getSunset() sunrise} or {@link #getSeaLevelSunrise() sea level sunrise} (depending on the {@link
	 * #isUseElevation()} setting). This is based on a 24-minute <a href=
	 * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> so the time for 4 mil is 96 minutes
	 * which is 1/7.5th of a day (12 * 60 / 7.5 = 96). The day is calculated from {@link #getSeaLevelSunrise() sea level sunrise}
	 * to {@link #getSeaLevelSunset() sea level sunset} or {@link #getSunset() sunrise} to {@link
	 *  getSunset() sunset} (depending on the {@link #isUseElevation()}. The actual calculation used is {@link
	 *  getSunriseBasedOnElevationSetting()} - ({@link #getShaahZmanisGRA()} * 1.6).
	 * 
	 * @return the <code>Instant</code> representing the time. If the calculation can't be computed such as in the Arctic
	 *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
	 *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
	 *         documentation.
	 * @see #getShaahZmanisGRA()
	 */
	public Instant getAlos96Zmanis() {
		return getZmanisBasedOffset(-1.6);
	}

	/**
	 * Method to return <em>alos</em> (dawn) calculated using 90 minutes before {@link #getSunset() sunrise} or
	 * {@link #getSeaLevelSunrise() sea level sunrise} (depending on the {@link #isUseElevation()} setting) based on the time
	 * to walk the distance of 4 <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> at
	 * 22.5 minutes a mil. Time-based offset calculations for <em>alos</em> are based on the opinion of the <em><a href=
	 * "https://en.wikipedia.org/wiki/Rishonim">Rishonim</a></em> who stated that the time of the <em>Neshef</em> (time between
	 * dawn and sunrise) does not vary by the time of year or location but purely depends on the time it takes to walk the
	 * distance of 4 mil.
	 * 
	 * @return the <code>Instant</code> representing the time. If the calculation can't be computed such as in the Arctic
	 *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
	 *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
	 *         documentation.
	 */
	public Instant getAlos90Minutes() {
		return getTimeOffset(getSunriseBasedOnElevationSetting(), -90 * MINUTE_MILLIS);
	}

	/**
	 * This method should be used <em>lechumra</em> only and returns <em>alos</em> (dawn) calculated using 120 minutes
	 * before {@link #getSunset() sunrise} or {@link #getSeaLevelSunrise() sea level sunrise} (depending on the
	 * {@link #isUseElevation()} setting) based on the time to walk the distance of 5 <a href=
	 * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> (<em>Ula</em>) at 24 minutes a
	 * mil. Time based offset calculations for <em>alos</em> are based on the* opinion of the <em><a href=
	 * "https://en.wikipedia.org/wiki/Rishonim">Rishonim</a></em> who stated that the time of the <em>neshef</em> (time
	 * between dawn and sunrise) does not vary by the time of year or location but purely depends on the time it takes to
	 * walk the distance of 5 mil (<em>Ula</em>). Since this time is extremely early, it should only be used <em>lechumra</em>,
	 * such as not eating after this time on a fast day, and not as the start time for <em>mitzvos</em> that can only be
	 * performed during the day.
	 * 
	 * @deprecated This method should be used <em>lechumra</em> only (such as stopping to eat at this time on a fast day),
	 *         since it returns a very early time, and if used <em>lekula</em> can result in doing <em>mitzvos hayom</em>
	 *         too early according to most opinions. There is no current plan to remove this method from the API, and this
	 *         deprecation is intended to alert developers of the danger of using it.
	 * 
	 * @return the <code>Instant</code> representing the time. If the calculation can't be computed such as in the Arctic
	 *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
	 *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
	 *         documentation.
	 * 
	 * @see #getTzais120Minutes()
	 * @see #getAlos26Degrees()
	 */
	@Deprecated (forRemoval=false)
	public Instant getAlos120Minutes() {
		return getTimeOffset(getSunriseBasedOnElevationSetting(), -120 * MINUTE_MILLIS);
	}

	/**
	 * This method should be used <em>lechumra</em> only and  method returns <em>alos</em> (dawn) calculated using
	 * 120 minutes <em>zmaniyos</em> or 1/6th of the day before {@link #getSunset() sunrise} or {@link
	 * #getSeaLevelSunrise() sea level sunrise} (depending on the {@link #isUseElevation()} setting). This is based
	 * on a 24-minute <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> so
	 * the time for 5 mil is 120 minutes which is 1/6th of a day (12 * 60 / 6 = 120). The day is calculated from
	 * {@link #getSeaLevelSunrise() sea level sunrise} to {@link #getSeaLevelSunset() sea level sunset} or {@link
	 * #getSunset() sunrise} to {@link #getSunset() sunset} (depending on the {@link
	 * #isUseElevation()}. The actual calculation used is {@link #getSunset()} - ({@link #getShaahZmanisGRA()}
	 * * 2). Since this time is extremely early, it should only be used <em>lechumra</em>, such as not eating after this time
	 * on a fast day, and not as the start time for <em>mitzvos</em> that can only be performed during the day.
	 * 
	 * @deprecated This method should be used <em>lechumra</em> only (such as stopping to eat at this time on a fast day),
	 *         since it returns a very early time, and if used <em>lekula</em> can result in doing <em>mitzvos hayom</em>
	 *         too early according to most opinions. There is no current plan to remove this method from the API, and this
	 *         deprecation is intended to alert developers of the danger of using it.
	 * 
	 * @return the <code>Instant</code> representing the time. If the calculation can't be computed such as in the Arctic
	 *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
	 *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
	 *         documentation.
	 * @see #getAlos120Minutes()
	 * @see #getAlos26Degrees()
	 */
	@Deprecated (forRemoval=false)
	public Instant getAlos120Zmanis() {
		return getZmanisBasedOffset(-2.0);
	}

	/**
	 * This method should be used <em>lechumra</em> only and returns <em>alos</em> (dawn) calculated when the sun is {@link
	 * ZENITH_26_DEGREES 26°} below the eastern geometric horizon before sunrise. This calculation is based on the same
	 * calculation of {@link #getAlos120Minutes() 120 minutes} but uses a degree-based calculation instead of 120 exact minutes.
	 * This calculation is based on the position of the sun 120 minutes before sunrise in Jerusalem <a href=
	 * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>, which
	 * calculates to 26° below {@link GEOMETRIC_ZENITH geometric zenith}. Since this time is extremely early, it should
	 * only be used <em>lechumra</em> only, such as not eating after this time on a fast day, and not as the start time for
	 * <em>mitzvos</em> that can only be performed during the day.
	 * 
	 * @deprecated This method should be used <em>lechumra</em> only (such as stopping to eat at this time on a fast day),
	 *         since it returns a very early time, and if used <em>lekula</em> can result in doing <em>mitzvos hayom</em>
	 *         too early according to most opinions. There is no current plan to remove this  method from the API, and this
	 *         deprecation is intended to alert developers of the danger of using it.
	 * 
	 * @return the <code>Instant</code> representing <em>alos</em>. If the calculation can't be computed such as northern
	 *         and southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun
	 *         may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned. See
	 *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getAlos120Minutes()
	 * @see #getTzais120Minutes()
	 * @see #getTzais26Degrees()
	 */
	@Deprecated (forRemoval=false)
	public Instant getAlos26Degrees() {
		return getSunriseOffsetByDegrees(ZENITH_26_DEGREES);
	}

	/**
	 * A method to return <em>alos</em> (dawn) calculated when the sun is {@link ASTRONOMICAL_ZENITH 18°} below the
	 * eastern geometric horizon before sunrise.
	 * 
	 * @return the <code>Instant</code> representing <em>alos</em>. If the calculation can't be computed such as northern
	 *         and southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun
	 *         may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned.
	 *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see ASTRONOMICAL_ZENITH
	 */
	public Instant getAlos18Degrees() {
		return getSunriseOffsetByDegrees(ASTRONOMICAL_ZENITH);
	}
	
	/**
	 * A method to return <em>alos</em> (dawn) calculated when the sun is {@link ZENITH_19_DEGREES 19°} below the
	 * eastern geometric horizon before sunrise. This is the <a href="https://en.wikipedia.org/wiki/Maimonides"
	 * >Rambam</a>'s <em>alos</em> according to Rabbi Moshe Kosower's <a href=
	 * "https://www.worldcat.org/oclc/145454098">Maaglei Tzedek</a>, page 88, <a href=
	 * "https://hebrewbooks.org/pdfpager.aspx?req=33464&pgnum=13">Ayeles Hashachar Vol. I, page 12</a>, <a href=
	 * "https://hebrewbooks.org/pdfpager.aspx?req=55960&pgnum=258">Yom Valayla Shel Torah, Ch. 34, p. 222</a> and 
	 * Rabbi Yaakov Shakow's <a href="https://www.worldcat.org/oclc/1043573513">Luach Ikvei Hayom</a>.
	 * 
	 * @return the <code>Instant</code> representing <em>alos</em>. If the calculation can't be computed such as northern
	 *         and southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun
	 *         may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned.
	 *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 */
	public Instant getAlos19Degrees() {
		return getSunriseOffsetByDegrees(ZENITH_19_DEGREES);
	}

	/**
	 * Method to return <em>alos</em> (dawn) calculated when the sun is {@link ZENITH_19_POINT_8 19.8°} below the
	 * eastern geometric horizon before sunrise. This calculation is based on the same calculation of
	 * {@link #getAlos90Minutes() 90 minutes} before sunrise, but uses a degree-based calculation instead of 90 exact minutes.
	 * This calculation is based on the position of the sun 90 minutes before sunrise in Jerusalem <a href=
	 * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>, which
	 * calculates to 19.8° below {@link GEOMETRIC_ZENITH geometric zenith}.
	 * 
	 * @return the <code>Instant</code> representing <em>alos</em>. If the calculation can't be computed such as northern
	 *         and southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun
	 *         may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned. See
	 *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getAlos90Minutes()
	 * @see #getTzais19Point8Degrees()
	 */
	public Instant getAlos19Point8Degrees() {
		return getSunriseOffsetByDegrees(ZENITH_19_POINT_8);
	}
	
	/**
	 * This method returns <em>misheyakir</em> based on the position of the sun {@link ZENITH_12_POINT_85 12.85°}
	 * below {@link GEOMETRIC_ZENITH geometric zenith} (90°). This is based on the position of the sun slightly
	 * later than 57 minutes before {@link #getSunset() sunrise} in Jerusalem <a href=
	 * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>. This
	 * <em>zman</em> is mentioned for use <b><em>bish'as hadchak</em></b> in the Birur Halacha <a href=
	 * "https://hebrewbooks.org/pdfpager.aspx?req=50535&st=&pgnum=88">Tinyana</a> and <a href=
	 * "https://hebrewbooks.org/pdfpager.aspx?req=50537&st=&pgnum=31">Tlisa'ah</a> in  Orach Chaim siman 18 as 12.85°.
	 * Actual calculations show it to be slightly more than 12.9°, but the Birur Halacha indicates that 12.85° is a
	 * slight <em>chumra</em> (on a <em>bedieved</em> time) VS the 12.9° that 57 minutes calculates as (a difference of
	 * about 14 seconds at the equinox/equilux in Jerusalem). The <em>zman</em> of 12.9° is also mentioned in the Piskei
	 * Tshuvos siman 18, page 190 (where a typo indicates that this is the degree equivalent to 60 minutes before sunrise,
	 * when in fact at that point the sun is about 13.5° below the horizon). The 57 minute based time is mentioned by the
	 * Minchas Yitzchak <a href="https://hebrewbooks.org/pdfpager.aspx?req=1601&st=&pgnum=21">vol. 9, siman 9</a> as 15 minutes
	 * before <em>alos hashachar</em> (though he is not clear what location he refers to, and does not mention a degree-based
	 * conversion). The Kaf Hachaim <a href="https://hebrewbooks.org/pdfpager.aspx?req=8140&st=&pgnum=81">vol.1 siman 18, no.
	 * 18</a> states that in Yerushalayim 60 fixed minutes are used year round. Calculations show that 60 fixed minutes in
	 * Yerushalayim ranges from 13.5° at the spring equinox to 11.5° at the summer solstice. 57-minute
	 * <em>misheyakir</em> range from 12.9° at the winter equinox to 11° at the summer solstice.
	 * Analysis of the difference between 12.85° and 12.9°, shows that the maximum difference occurs at the summer
	 * solstice. In Lakewood, NJ at a latitude of 40.096°, the maximum difference throughout the year is 23 seconds.
	 * In the winter where there is the greatest need for very early <em>misheyakir</em> times, the difference is in the 16
	 * second range. Going north to Montreal at latitude 45.5°, the maximum is 29 seconds and is about 18 seconds in the
	 * winter. Moving farther north to the latitude of Vilnius at a latitude of 54.68°, things change. Firstly, around the
	 * summer solstice it will not reach that far below the horizon. On the dates that both can be calculated, the maximum
	 * difference can be pretty high on one or two days of the year (around Jul 8),  with about a week having over a two minute
	 * difference between the two. Even at the latitude of Vilna, from Dec - March, the difference is about 22 seconds.
	 * 
	 * @deprecated This method returns a very early <em>misheyakir</em> time that should only be used <b><em>bish'as
	 *         hadchak</em></b>. <em>Lechatchila</em>, a later <em>zman</em> should be used. There is no current plan to remove
	 *         this method from the API, and this deprecation is intended to notify developers to add an alert to users of
	 *         the risk of using it.
	 * 
	 * @return The <code>Instant</code> of <em>misheyakir</em>. If the calculation can't be computed such as northern and
	 *         southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may
	 *         not reach low enough below the horizon for this calculation, a <code>null</code> will be returned. See
	 *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see ZENITH_12_POINT_85
	 */
	@Deprecated (forRemoval=false)
	public Instant getMisheyakir12Point85Degrees() {
		return getSunriseOffsetByDegrees(ZENITH_12_POINT_85);
	}

	/**
	 * This method returns <em>misheyakir</em> based on the position of the sun when it is {@link ZENITH_11_DEGREES
	 * 11.5°} below {@link GEOMETRIC_ZENITH geometric zenith} (90°). This calculation is used for calculating
	 * <em>misheyakir</em> according to some opinions. This calculation is based on the position of the sun 52 minutes
	 * before {@link #getSunset() sunrise} in Jerusalem <a href=
	 * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>,
	 * which calculates to 11.5° below {@link GEOMETRIC_ZENITH geometric zenith}.
	 * @todo recalculate.
	 * 
	 * @return the <code>Instant</code> of <em>misheyakir</em>. If the calculation can't be computed such as northern and
	 *         southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may
	 *         not reach low enough below the horizon for this calculation, a <code>null</code> will be returned. See
	 *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see ZENITH_11_POINT_5
	 */
	public Instant getMisheyakir11Point5Degrees() {
		return getSunriseOffsetByDegrees(ZENITH_11_POINT_5);
	}

	/**
	 * This method returns <em>misheyakir</em> based on the position of the sun when it is {@link ZENITH_11_DEGREES
	 * 11°} below {@link GEOMETRIC_ZENITH geometric zenith} (90°). This calculation is used for calculating
	 * <em>misheyakir</em> according to some opinions. This calculation is based on the position of the sun 48 minutes
	 * before {@link #getSunset() sunrise} in Jerusalem <a href=
	 * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>,
	 * which calculates to 11° below {@link GEOMETRIC_ZENITH geometric zenith}.
	 * 
	 * @return If the calculation can't be computed such as northern and southern locations even south of the Arctic
	 *         Circle and north of the Antarctic Circle where the sun may not reach low enough below the horizon for
	 *         this calculation, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see ZENITH_11_DEGREES
	 */
	public Instant getMisheyakir11Degrees() {
		return getSunriseOffsetByDegrees(ZENITH_11_DEGREES);
	}

	/**
	 * This method returns <em>misheyakir</em> based on the position of the sun when it is {@link ZENITH_10_POINT_2
	 * 10.2°} below {@link GEOMETRIC_ZENITH geometric zenith} (90°). This calculation is used for calculating
	 * <em>misheyakir</em> according to some opinions. This calculation is based on the position of the sun 45 minutes
	 * before {@link #getSunset() sunrise} in Jerusalem <a href=
	 * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox</a> which calculates
	 * to 10.2° below {@link GEOMETRIC_ZENITH geometric zenith}.
	 * 
	 * @return the <code>Instant</code> of <em>misheyakir</em>. If the calculation can't be computed such as
	 *         northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle where
	 *         the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned
	 *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see ZENITH_10_POINT_2
	 */
	public Instant getMisheyakir10Point2Degrees() {
		return getSunriseOffsetByDegrees(ZENITH_10_POINT_2);
	}
	
	/**
	 * This method returns <em>misheyakir</em> based on the position of the sun when it is {@link ZENITH_7_POINT_65
	 * 7.65°} below {@link GEOMETRIC_ZENITH geometric zenith} (90°). The degrees are based on a 35/36 minute
	 * <em>zman</em> <a href="https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the
	 * equinox / equilux</a>, when the <em>neshef</em> (twilight) is the shortest. This time is based on <a href=
	 * "https://en.wikipedia.org/wiki/Moshe_Feinstein">Rabbi Moshe Feinstein</a> who writes in <a href=
	 * "https://hebrewbooks.org/pdfpager.aspx?req=14677&pgnum=7">Ohr Hachaim Vol. 4, Ch. 6</a>
	 * that <em>misheyakir</em> in New York is 35-40 minutes before sunrise, something that is a drop less than 8°.
	 * <a href="https://en.wikipedia.org/wiki/Yisroel_Taplin">Rabbi Yisroel Taplin</a> in <a href=
	 * "https://www.worldcat.org/oclc/889556744">Zmanei Yisrael</a> (page 117) notes that <a href=
	 * "https://en.wikipedia.org/wiki/Yaakov_Kamenetsky">Rabbi Yaakov Kamenetsky</a> stated that it is not less than 36
	 * minutes before sunrise (maybe it is 40 minutes). Sefer Yisrael Vehazmanim (p. 7) quotes the Tamar Yifrach
	 * in the name of the <a href="https://en.wikipedia.org/wiki/Joel_Teitelbaum">Satmar Rov</a> that one should be stringent
	 * not consider <em>misheyakir</em> before 36 minutes. This is also the accepted <a href=
	 * "https://en.wikipedia.org/wiki/Minhag">minhag</a> in <a href=
	 * "https://en.wikipedia.org/wiki/Lakewood_Township,_New_Jersey">Lakewood</a> that is used in the <a href=
	 * "https://en.wikipedia.org/wiki/Beth_Medrash_Govoha">Yeshiva</a>. This follows the opinion of <a href=
	 * "https://en.wikipedia.org/wiki/Shmuel_Kamenetsky">Rabbi Shmuel Kamenetsky</a> who provided the time of 35/36 minutes,
	 * but did not provide a degree-based time. Since this <em>zman</em> depends on the level of light, Rabbi Yaakov Shakow
	 * presented this degree-based calculations to Rabbi Shmuel Kamenetsky who agreed to them.
	 * 
	 * @return the <code>Instant</code> of <em>misheyakir</em>. If the calculation can't be computed such as
	 *         northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle where
	 *         the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned.
	 *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * 
	 * @see ZENITH_7_POINT_65
	 * @see #getMisheyakir9Point5Degrees()
	 */
	public Instant getMisheyakir7Point65Degrees() {
		return getSunriseOffsetByDegrees(ZENITH_7_POINT_65);
	}
	
	/**
	 * This method returns <em>misheyakir</em> based on the position of the sun when it is {@link ZENITH_9_POINT_5
	 * 9.5°} below {@link GEOMETRIC_ZENITH geometric zenith} (90°). This calculation is based on <a href=
	 * "https://en.wikipedia.org/wiki/Dovid_Kronglas">Rabbi Dovid Kronglass's</a> Calculation of 45 minutes in Baltimore
	 * as mentioned in <a href="https://hebrewbooks.org/pdfpager.aspx?req=20287&pgnum=29">Divrei Chachamim No. 24</a>
	 * brought down by the <a href="https://hebrewbooks.org/pdfpager.aspx?req=50535&pgnum=87">Birur Halacha, Tinyana, Ch.
	 * 18</a>. This calculates to 9.5°. Also see <a href="https://en.wikipedia.org/wiki/Jacob_Isaac_Neiman">Rabbi Yaakov
	 * Yitzchok Neiman</a> in Kovetz Eitz Chaim Vol. 9, p. 202 that the Vya'an Yosef did not want to rely on times earlier
	 * than 45 minutes in New York. This <em>zman</em> is also used in the calendars published by Rabbi Hershel Edelstein.
	 * As mentioned in Yisroel Vehazmanim, Rabbi Edelstein who was given the 45 minute <em>zman</em> by Rabbi Bick. The
	 * calendars published by the <em><a href="https://en.wikipedia.org/wiki/Mizrahi_Jews">Edot Hamizrach</a></em> communities
	 * also use this <em>zman</em>. This also follows the opinion of <a href="https://en.wikipedia.org/wiki/Shmuel_Kamenetsky"
	 * >Rabbi Shmuel Kamenetsky</a> who provided the time of 36 and 45 minutes, but did not provide a degree-based time. Since
	 * this <em>zman</em> depends on the level of light, Rabbi Yaakov Shakow presented these degree-based times to Rabbi Shmuel
	 * Kamenetsky who agreed to them.
	 * 
	 * @return the <code>Instant</code> of <em>misheyakir</em>. If the calculation can't be computed such as
	 *         northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle where
	 *         the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned.
	 *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * 
	 * @see ZENITH_9_POINT_5
	 * @see #getMisheyakir7Point65Degrees()
	 */
	public Instant getMisheyakir9Point5Degrees() {
		return getSunriseOffsetByDegrees(ZENITH_9_POINT_5);
	}

	/**
	 * This method returns the latest <em>zman krias shema</em> (time to recite Shema in the morning) according to the
	 * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on
	 * <em>alos</em> being {@link #getAlos19Point8Degrees() 19.8°} before {@link #getSunset() sunrise}. This
	 * time is 3 {@link #getShaahZmanis19Point8Degrees() <em>shaos zmaniyos</em>} (solar hours) after {@link
	 * #getAlos19Point8Degrees() dawn} based on the opinion of the MGA that the day is calculated from dawn to nightfall
	 * with both being 19.8° below sunrise or sunset. This returns the time of 3 *
	 * {@link #getShaahZmanis19Point8Degrees()} after {@link #getAlos19Point8Degrees() dawn}.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
	 *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
	 *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis19Point8Degrees()
	 * @see #getAlos19Point8Degrees()
	 */
	public Instant getSofZmanShmaMGA19Point8Degrees() {
		return getSofZmanShma(getAlos19Point8Degrees(), getTzais19Point8Degrees(), true);
	}

	/**
	 * This method returns the latest <em>zman krias shema</em> (time to recite Shema in the morning) according to the opinion of
	 * the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
	 * #getAlos16Point1Degrees() 16.1°} before {@link #getSunset() sunrise}. This time is 3 {@link
	 * #getShaahZmanis16Point1Degrees() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos16Point1Degrees() dawn} based on
	 * the opinion of the MGA that the day is calculated from dawn to nightfall with both being 16.1° below sunrise or sunset.
	 * This returns the time of 3 * {@link #getShaahZmanis16Point1Degrees()} after {@link #getAlos16Point1Degrees() dawn}.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
	 *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
	 *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis16Point1Degrees()
	 * @see #getAlos16Point1Degrees()
	 */
	public Instant getSofZmanShmaMGA16Point1Degrees() {
		return getSofZmanShma(getAlos16Point1Degrees(), getTzais16Point1Degrees(), true);
	}

	/**
	 * This method returns the latest <em>zman krias shema</em> (time to recite Shema in the morning) according to the
	 * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based
	 * on <em>alos</em> being {@link #getAlos18Degrees() 18°} before {@link #getSunset() sunrise}. This time is 3
	 * {@link #getShaahZmanis18Degrees() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos18Degrees() dawn}
	 * based on the opinion of the MGA that the day is calculated from dawn to nightfall with both being 18°
	 * below sunrise or sunset. This returns the time of 3 * {@link #getShaahZmanis18Degrees()} after
	 * {@link #getAlos18Degrees() dawn}.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
	 *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
	 *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis18Degrees()
	 * @see #getAlos18Degrees()
	 */
	public Instant getSofZmanShmaMGA18Degrees() {
		return getSofZmanShma(getAlos18Degrees(), getTzais18Degrees(), true);
	}

	/**
	 * This method returns the latest <em>zman krias shema</em> (time to recite <em>Shema</em> in the morning) according
	 * to the opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based
	 * on <em>alos</em> being {@link #getAlos72Zmanis() 72} minutes <em>zmaniyos</em>, or 1/10th of the day before
	 * {@link #getSunset() sunrise}. This time is 3 {@link #getShaahZmanis90MinutesZmanis() <em>shaos zmaniyos</em>}
	 * (solar hours) after {@link #getAlos72Zmanis() dawn} based on the opinion of the MGA that the day is calculated
	 * from a {@link #getAlos72Zmanis() dawn} of 72 minutes <em>zmaniyos</em>, or 1/10th of the day before
	 * {@link #getSeaLevelSunrise() sea level sunrise} to {@link #getTzais72Zmanis() nightfall} of 72 minutes
	 * <em>zmaniyos</em> after {@link #getSeaLevelSunset() sea level sunset}. This returns the time of 3 *
	 * {@link #getShaahZmanis72MinutesZmanis()} after {@link #getAlos72Zmanis() dawn}.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
	 *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis72MinutesZmanis()
	 * @see #getAlos72Zmanis()
	 * @see #isUseAstronomicalChatzosForOtherZmanim()
	 */
	public Instant getSofZmanShmaMGA72MinutesZmanis() {
		return getSofZmanShma(getAlos72Zmanis(), getTzais72Zmanis(), true);
	}

	/**
	 * This method returns the latest <em>zman krias shema</em> (time to recite <em>Shema</em> in the morning) according
	 * to the opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on
	 * <em>alos</em> being {@link #getAlos90Minutes() 90} minutes before {@link #getSunset() sunrise}. This time is 3
	 * {@link #getShaahZmanis90Minutes() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos90Minutes() dawn} based on
	 * the opinion of the MGA that the day is calculated from a {@link #getAlos90Minutes() dawn} of 90 minutes before sunrise to
	 * {@link #getTzais90Minutes() nightfall} of 90 minutes after sunset. This returns the time of 3 *
	 * {@link #getShaahZmanis90Minutes()} after {@link #getAlos90Minutes() dawn}.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
	 *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis90Minutes()
	 * @see #getAlos90Minutes()
	 * @see #isUseAstronomicalChatzosForOtherZmanim()
	 */
	public Instant getSofZmanShmaMGA90Minutes() {
		return getSofZmanShma(getAlos90Minutes(), getTzais90Minutes(), true);
	}

	/**
	 * This method returns the latest <em>zman krias shema</em> (time to recite Shema in the morning) according to the
	 * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based
	 * on <em>alos</em> being {@link #getAlos90Zmanis() 90} minutes <em>zmaniyos</em> before {@link #getSunset()
	 * sunrise}. This time is 3 {@link #getShaahZmanis90MinutesZmanis() <em>shaos zmaniyos</em>} (solar hours) after
	 * {@link #getAlos90Zmanis() dawn} based on the opinion of the MGA that the day is calculated from a {@link
	 * #getAlos90Zmanis() dawn} of 90 minutes <em>zmaniyos</em> before sunrise to {@link #getTzais90Zmanis() nightfall}
	 * of 90 minutes <em>zmaniyos</em> after sunset. This returns the time of 3 * {@link #getShaahZmanis90MinutesZmanis()}
	 * after {@link #getAlos90Zmanis() dawn}.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
	 *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis90MinutesZmanis()
	 * @see #getAlos90Zmanis()
	 * @see #isUseAstronomicalChatzosForOtherZmanim()
	 */
	public Instant getSofZmanShmaMGA90MinutesZmanis() {
		return getSofZmanShma(getAlos90Zmanis(), getTzais90Zmanis(), true);
	}

	/**
	 * This method returns the latest <em>zman krias shema</em> (time to recite Shema in the morning) according to the opinion of
	 * the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
	 * #getAlos96Minutes() 96} minutes before {@link #getSunset() sunrise}. This time is 3 {@link
	 * #getShaahZmanis96Minutes() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos96Minutes() dawn} based on the opinion
	 * of the MGA that the day is calculated from a {@link #getAlos96Minutes() dawn} of 96 minutes before sunrise to {@link
	 * #getTzais96Minutes() nightfall} of 96 minutes after sunset. This returns the time of 3 * {@link #getShaahZmanis96Minutes()}
	 * after {@link #getAlos96Minutes() dawn}.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
	 *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis96Minutes()
	 * @see #getAlos96Minutes()
	 * @see #isUseAstronomicalChatzosForOtherZmanim()
	 */
	public Instant getSofZmanShmaMGA96Minutes() {
		return getSofZmanShma(getAlos96Minutes(), getTzais96Minutes(), true);
	}

	/**
	 * This method returns the latest <em>zman krias shema</em> (time to recite Shema in the morning) according to the
	 * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based
	 * on <em>alos</em> being {@link #getAlos90Zmanis() 96} minutes <em>zmaniyos</em> before {@link #getSunset()
	 * sunrise}. This time is 3 {@link #getShaahZmanis96MinutesZmanis() <em>shaos zmaniyos</em>} (solar hours) after
	 * {@link #getAlos96Zmanis() dawn} based on the opinion of the MGA that the day is calculated from a {@link
	 * #getAlos96Zmanis() dawn} of 96 minutes <em>zmaniyos</em> before sunrise to {@link #getTzais90Zmanis() nightfall}
	 * of 96 minutes <em>zmaniyos</em> after sunset. This returns the time of 3 * {@link #getShaahZmanis96MinutesZmanis()}
	 * after {@link #getAlos96Zmanis() dawn}.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
	 *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis96MinutesZmanis()
	 * @see #getAlos96Zmanis()
	 * @see #isUseAstronomicalChatzosForOtherZmanim()
	 */
	public Instant getSofZmanShmaMGA96MinutesZmanis() {
		return getSofZmanShma(getAlos96Zmanis(), getTzais96Zmanis(), true);
	}

	/**
	 * This method returns the latest <em>zman krias shema</em> (time to recite <em>Shema</em> in the morning) calculated
	 * as 3 hours (regular clock hours and not <em>shaos zmaniyos</em>) before {@link #getChatzosHayom()}.
	 * Generally known as part of the "Komarno" <em>zmanim</em> after <a href=
	 * "https://en.wikipedia.org/wiki/Komarno_(Hasidic_dynasty)#Rabbi_Yitzchak_Eisik_Safrin">Rav Yitzchak Eizik of
	 * Komarno</a>, a proponent of this calculation, it actually predates him a lot. It is the opinion of the 
	 * <em>Shach</em> in the Nekudas Hakesef (Yoreh Deah 184), <a href=
	 * "https://hebrewbooks.org/pdfpager.aspx?req=21638&st=&pgnum=30">Rav Moshe Lifshitz</a> in his commentary
	 * <a href="https://hebrewbooks.org/pdfpager.aspx?req=21638&st=&pgnum=50">Lechem Mishneh on Brachos 1:2</a>. It is
	 * next brought down about 100 years later by the <a href="https://en.wikipedia.org/wiki/Jacob_Emden">Yaavetz</a>
	 * (in his <em>siddur</em>, <a href="https://hebrewbooks.org/pdfpager.aspx?req=7920&st=&pgnum=6">Mor Uktziah Orach
	 * Chaim 1</a>, <a href="https://hebrewbooks.org/pdfpager.aspx?req=22309&st=&pgnum=30">Lechem Shamayim, Brachos 1:2</a>
	 * and <a href="https://hebrewbooks.org/pdfpager.aspx?req=1408&st=&pgnum=69">She'elos Yaavetz vol. 1 no. 40</a>),
	 * Rav Yitzchak Eizik of Komarno in the Ma'aseh Oreg on Mishnayos Brachos 11:2, Shevus Yaakov, Chasan Sofer and others.
	 * See Yisrael Vehazmanim <a href="https://hebrewbooks.org/pdfpager.aspx?req=9765&st=&pgnum=83">vol. 1 7:3, page 55 -
	 * 62</a>.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
	 *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getChatzosHayom()
	 * @see #getSofZmanTfila2HoursBeforeChatzos()
	 * @see #isUseAstronomicalChatzos()
	 */
	public Instant getSofZmanShma3HoursBeforeChatzos() {
		return getTimeOffset(getChatzosHayom(), -180 * MINUTE_MILLIS);
	}

	/**
	 * This method returns the latest <em>zman krias shema</em> (time to recite Shema in the morning) according to the
	 * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based
	 * on <em>alos</em> being {@link #getAlos120Minutes() 120} minutes or 1/6th of the day before {@link #getSunset()
	 * sunrise}. This time is 3 {@link #getShaahZmanis120Minutes() <em>shaos zmaniyos</em>} (solar hours) after {@link
	 * #getAlos120Minutes() dawn} based on the opinion of the MGA that the day is calculated from a {@link #getAlos120Minutes() dawn}
	 * of 120 minutes before sunrise to {@link #getTzais120Minutes() nightfall} of 120 minutes after sunset. This returns the time of
	 * 3 {@link #getShaahZmanis120Minutes()} after {@link #getAlos120Minutes() dawn}. This is an extremely early <em>zman</em> that
	 * is very much a <em>chumra</em>.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
	 *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis120Minutes()
	 * @see #getAlos120Minutes()
	 * @see #isUseAstronomicalChatzosForOtherZmanim()
	 */
	public Instant getSofZmanShmaMGA120Minutes() {
		return getSofZmanShma(getAlos120Minutes(), getTzais120Minutes(), true);
	}

	/**
	 * This method returns the latest <em>zman krias shema</em> (time to recite <em>Shema</em> in the morning) based on the
	 * opinion that the day starts at {@link #getAlos16Point1Degrees() <em>alos</em> 16.1°} and ends at {@link
	 * #getSeaLevelSunset() sea level sunset}. This is the opinion of the <a href=
	 * "https://hebrewbooks.org/40357">\u05D7\u05D9\u05D3\u05D5\u05E9\u05D9
	 * \u05D5\u05DB\u05DC\u05DC\u05D5\u05EA \u05D4\u05E8\u05D6\u05F4\u05D4</a> and the <a href=
	 * "https://hebrewbooks.org/14799">\u05DE\u05E0\u05D5\u05E8\u05D4 \u05D4\u05D8\u05D4\u05D5\u05E8\u05D4</a> as
	 * mentioned by Yisrael Vehazmanim <a href="https://hebrewbooks.org/pdfpager.aspx?req=9765&pgnum=81">vol 1, sec. 7,
	 * ch. 3 no. 16</a>. Three <em>shaos zmaniyos</em> are calculated based on this day and added to {@link
	 * #getAlos16Point1Degrees() <em>alos</em>} to reach this time. This time is 3 <em>shaos zmaniyos</em> (solar hours)
	 * after {@link #getAlos16Point1Degrees() dawn} based on the opinion that the day is calculated from a {@link
	 * #getAlos16Point1Degrees() <em>alos</em> 16.1°} to {@link #getSeaLevelSunset() sea level sunset}.
	 * <b>Note: </b> Based on this calculation <em>chatzos</em> will not be at midday and {@link
	 * #isUseAstronomicalChatzosForOtherZmanim()} will be ignored.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em> based on this day. If the calculation can't
	 *         be computed such as northern and southern locations even south of the Arctic Circle and north of the
	 *         Antarctic Circle where the sun may not reach low enough below the horizon for this calculation, a null
	 *         will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getAlos16Point1Degrees()
	 * @see #getSeaLevelSunset()
	 */
	public Instant getSofZmanShmaAlos16Point1ToSunset() {
		return getSofZmanShma(getAlos16Point1Degrees(), getSunsetBasedOnElevationSetting(), false);
	}

	/**
	 * This method returns the latest <em>zman krias shema</em> (time to recite Shema in the morning) based on the
	 * opinion that the day starts at {@link #getAlos16Point1Degrees() <em>alos</em> 16.1°} and ends at
	 * {@link #getTzaisGeonim7Point083Degrees() <em>tzais</em> 7.083°}. 3 <em>shaos zmaniyos</em> are calculated
	 * based on this day and added to {@link #getAlos16Point1Degrees() <em>alos</em>} to reach this time. This time is 3
	 * <em>shaos zmaniyos</em> (temporal hours) after {@link #getAlos16Point1Degrees() <em>alos</em> 16.1°} based on
	 * the opinion that the day is calculated from a {@link #getAlos16Point1Degrees() <em>alos</em> 16.1°} to
	 * {@link #getTzaisGeonim7Point083Degrees() <em>tzais</em> 7.083°}.
	 * <b>Note: </b> Based on this calculation <em>chatzos</em> will not be at midday and {@link
	 * #isUseAstronomicalChatzosForOtherZmanim()} will be ignored.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em> based on this calculation. If the
	 *         calculation can't be computed such as northern and southern locations even south of the Arctic Circle and
	 *         north of the Antarctic Circle where the sun may not reach low enough below the horizon for this
	 *         calculation, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getAlos16Point1Degrees()
	 * @see #getTzaisGeonim7Point083Degrees()
	 */
	public Instant getSofZmanShmaAlos16Point1ToTzaisGeonim7Point083Degrees() {
		return getSofZmanShma(getAlos16Point1Degrees(), getTzaisGeonim7Point083Degrees(), false);
	}

	/**
	 * This method returns the latest <em>zman tfila</em> (time to recite the morning prayers) according to the opinion
	 * of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on
	 * <em>alos</em> being {@link #getAlos19Point8Degrees() 19.8°} before {@link #getSunset() sunrise}. This time
	 * is 4 {@link #getShaahZmanis19Point8Degrees() <em>shaos zmaniyos</em>} (solar hours) after {@link
	 * #getAlos19Point8Degrees() dawn} based on the opinion of the MGA that the day is calculated from dawn to
	 * nightfall with both being 19.8° below sunrise or sunset. This returns the time of 4 * {@link
	 * #getShaahZmanis19Point8Degrees()} after {@link #getAlos19Point8Degrees() dawn}.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
	 *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
	 *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getShaahZmanis19Point8Degrees()
	 * @see #getAlos19Point8Degrees()
	 * @see #isUseAstronomicalChatzosForOtherZmanim()
	 */
	public Instant getSofZmanTfilaMGA19Point8Degrees() {
		return getSofZmanTfila(getAlos19Point8Degrees(), getTzais19Point8Degrees(), true);
	}

	/**
	 * This method returns the latest <em>zman tfila</em> (time to recite the morning prayers) according to the opinion
	 * of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on
	 * <em>alos</em> being {@link #getAlos16Point1Degrees() 16.1°} before {@link #getSunset() sunrise}. This time
	 * is 4 {@link #getShaahZmanis16Point1Degrees() <em>shaos zmaniyos</em>} (solar hours) after {@link
	 * #getAlos16Point1Degrees() dawn} based on the opinion of the MGA that the day is calculated from dawn to
	 * nightfall with both being 16.1° below sunrise or sunset. This returns the time of 4 * {@link
	 * #getShaahZmanis16Point1Degrees()} after {@link #getAlos16Point1Degrees() dawn}.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
	 *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
	 *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getShaahZmanis16Point1Degrees()
	 * @see #getAlos16Point1Degrees()
	 */
	public Instant getSofZmanTfilaMGA16Point1Degrees() {
		return getSofZmanTfila(getAlos16Point1Degrees(), getTzais16Point1Degrees(), true);
	}

	/**
	 * This method returns the latest <em>zman tfila</em> (time to recite the morning prayers) according to the opinion
	 * of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on
	 * <em>alos</em> being {@link #getAlos18Degrees() 18°} before {@link #getSunset() sunrise}. This time is 4
	 * {@link #getShaahZmanis18Degrees() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos18Degrees() dawn}
	 * based on the opinion of the MGA that the day is calculated from dawn to nightfall with both being 18°
	 * below sunrise or sunset. This returns the time of 4 * {@link #getShaahZmanis18Degrees()} after
	 * {@link #getAlos18Degrees() dawn}.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
	 *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
	 *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getShaahZmanis18Degrees()
	 * @see #getAlos18Degrees()
	 */
	public Instant getSofZmanTfilaMGA18Degrees() {
		return getSofZmanTfila(getAlos18Degrees(), getTzais18Degrees(), true);
	}

	/**
	 * This method returns the latest <em>zman tfila</em> (time to the morning prayers) according to the opinion of the
	 * <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em>
	 * being {@link #getAlos72Zmanis() 72} minutes <em>zmaniyos</em> before {@link #getSunset() sunrise}. This time is 4
	 * {@link #getShaahZmanis72MinutesZmanis() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos72Zmanis() dawn}
	 * based on the opinion of the MGA that the day is calculated from a {@link #getAlos72Zmanis() dawn} of 72
	 * minutes <em>zmaniyos</em> before sunrise to {@link #getTzais72Zmanis() nightfall} of 72 minutes <em>zmaniyos</em>
	 * after sunset. This returns the time of 4 * {@link #getShaahZmanis72MinutesZmanis()} after {@link #getAlos72Zmanis() dawn}.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
	 *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis72MinutesZmanis()
	 * @see #getAlos72Zmanis()
	 */
	public Instant getSofZmanTfilaMGA72MinutesZmanis() {
		return getSofZmanTfila(getAlos72Zmanis(), getTzais72Zmanis(), true);
	}

	/**
	 * This method returns the latest <em>zman tfila</em> (time to recite the morning prayers) according to the opinion
	 * of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on
	 * <em>alos</em> being {@link #getAlos90Minutes() 90} minutes before {@link #getSunset() sunrise}. This time is 4
	 * {@link #getShaahZmanis90Minutes() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos90Minutes() dawn} based on
	 * the opinion of the MGA that the day is calculated from a {@link #getAlos90Minutes() dawn} of 90 minutes before sunrise to
	 * {@link #getTzais90Minutes() nightfall} of 90 minutes after sunset. This returns the time of 4 *
	 * {@link #getShaahZmanis90Minutes()} after {@link #getAlos90Minutes() dawn}.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman tfila</em>. If the calculation can't be computed such as in
	 *         the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
	 *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis90Minutes()
	 * @see #getAlos90Minutes()
	 */
	public Instant getSofZmanTfilaMGA90Minutes() {
		return getSofZmanTfila(getAlos90Minutes(), getTzais90Minutes(), true);
	}

	/**
	 * This method returns the latest <em>zman tfila</em> (time to the morning prayers) according to the opinion of the
	 * <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em>
	 * being {@link #getAlos90Zmanis() 90} minutes <em>zmaniyos</em> before {@link #getSunset() sunrise}. This time is
	 * 4 {@link #getShaahZmanis90MinutesZmanis() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos90Zmanis()
	 * dawn} based on the opinion of the MGA that the day is calculated from a {@link #getAlos90Zmanis() dawn}
	 * of 90 minutes <em>zmaniyos</em> before sunrise to {@link #getTzais90Zmanis() nightfall} of 90 minutes
	 * <em>zmaniyos</em> after sunset. This returns the time of 4 * {@link #getShaahZmanis90MinutesZmanis()} after
	 * {@link #getAlos90Zmanis() dawn}.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
	 *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis90MinutesZmanis()
	 * @see #getAlos90Zmanis()
	 */
	public Instant getSofZmanTfilaMGA90MinutesZmanis() {
		return getSofZmanTfila(getAlos90Zmanis(), getTzais90Zmanis(), true);
	}

	/**
	 * This method returns the latest <em>zman tfila</em> (time to recite the morning prayers) according to the opinion
	 * of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on
	 * <em>alos</em> being {@link #getAlos96Minutes() 96} minutes before {@link #getSunset() sunrise}. This time is 4
	 * {@link #getShaahZmanis96Minutes() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos96Minutes() dawn} based on
	 * the opinion of the MGA that the day is calculated from a {@link #getAlos96Minutes() dawn} of 96 minutes before
	 * sunrise to {@link #getTzais96Minutes() nightfall} of 96 minutes after sunset. This returns the time of 4 *
	 * {@link #getShaahZmanis96Minutes()} after {@link #getAlos96Minutes() dawn}.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman tfila</em>. If the calculation can't be computed such as in
	 *         the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
	 *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis96Minutes()
	 * @see #getAlos96Minutes()
	 */
	public Instant getSofZmanTfilaMGA96Minutes() {
		return getSofZmanTfila(getAlos96Minutes(), getTzais96Minutes(), true);
	}

	/**
	 * This method returns the latest <em>zman tfila</em> (time to the morning prayers) according to the opinion of the
	 * <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em>
	 * being {@link #getAlos96Zmanis() 96} minutes <em>zmaniyos</em> before {@link #getSunset() sunrise}. This time is
	 * 4 {@link #getShaahZmanis96MinutesZmanis() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos96Zmanis()
	 * dawn} based on the opinion of the MGA that the day is calculated from a {@link #getAlos96Zmanis() dawn}
	 * of 96 minutes <em>zmaniyos</em> before sunrise to {@link #getTzais96Zmanis() nightfall} of 96 minutes
	 * <em>zmaniyos</em> after sunset. This returns the time of 4 * {@link #getShaahZmanis96MinutesZmanis()} after
	 * {@link #getAlos96Zmanis() dawn}.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
	 *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis90MinutesZmanis()
	 * @see #getAlos90Zmanis()
	 */
	public Instant getSofZmanTfilaMGA96MinutesZmanis() {
		return getSofZmanTfila(getAlos96Zmanis(), getTzais96Zmanis(), true);
	}

	/**
	 * This method returns the latest <em>zman tfila</em> (time to recite the morning prayers) according to the opinion
	 * of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on
	 * <em>alos</em> being {@link #getAlos120Minutes() 120} minutes before {@link #getSunset() sunrise} . This time is 4
	 * {@link #getShaahZmanis120Minutes() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos120Minutes() dawn}
	 * based on the opinion of the MGA that the day is calculated from a {@link #getAlos120Minutes() dawn} of 120
	 * minutes before sunrise to {@link #getTzais120Minutes() nightfall} of 120 minutes after sunset. This returns the time of
	 * 4 * {@link #getShaahZmanis120Minutes()} after {@link #getAlos120Minutes() dawn}. This is an extremely early <em>zman</em>
	 * that is very much a <em>chumra</em>.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
	 *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis120Minutes()
	 * @see #getAlos120Minutes()
	 */
	public Instant getSofZmanTfilaMGA120Minutes() {
		return getSofZmanTfila(getAlos120Minutes(), getTzais120Minutes(), true);
	}

	/**
	 * This method returns the latest <em>zman tfila</em> (time to recite the morning prayers) calculated as 2 hours
	 * before {@link #getChatzosHayom()}. This is based on the opinions that calculate
	 * <em>sof zman krias shema</em> as {@link #getSofZmanShma3HoursBeforeChatzos()}. This returns the time of 2 hours
	 * before {@link #getChatzosHayom()}.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where
	 *         it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getChatzosHayom()
	 * @see #getSofZmanShma3HoursBeforeChatzos()
	 */
	public Instant getSofZmanTfila2HoursBeforeChatzos() {
		return getTimeOffset(getChatzosHayom(), -120 * MINUTE_MILLIS);
	}

	/**
	 * This method returns <em>mincha gedola</em> calculated as 30 minutes after {@link #getChatzosHayom() <em>chatzos</em>}
	 * and not 1/2 of a {@link #getShaahZmanisGRA() <em>shaah zmanis</em>} after {@link #getChatzosHayom() <em>chatzos</em>} as
	 * calculated by {@link #getMinchaGedola}. Some use this time to delay the start of <em>mincha</em> in the winter when
	 * 1/2 of a {@link #getShaahZmanisGRA() <em>shaah zmanis</em>} is less than 30 minutes. See
	 * {@link #getMinchaGedolaGreaterThan30(Instant)} for a convenience method that returns the later of the 2 calculations. One
	 * should not use this time to start <em>mincha</em> before the standard {@link #getMinchaGedolaGRA() <em>mincha gedola</em>}.
	 * See Shulchan Aruch <a href="https://hebrewbooks.org/pdfpager.aspx?req=49624&st=&pgnum=291">Orach Chayim 234:1</a> and
	 * the Shaar Hatziyon <em>seif katan ches</em>. Since this calculation is a fixed 30 minutes of regular clock time after
	 * <em>chatzos</em>, even if {@link #isUseAstronomicalChatzosForOtherZmanim()} is <code>false</code>, this <em>mincha
	 * gedola</em> time will be affected by {@link #isUseAstronomicalChatzos()} and not by
	 * {@link #isUseAstronomicalChatzosForOtherZmanim()}.
	 * 
	 * @return the <code>Instant</code> of 30 minutes after <em>chatzos</em>. If the calculation can't be computed such as
	 *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
	 *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @todo Consider adjusting this to calculate the time as half an hour after {@link #getChatzosHayom()} that uses
	 *         {@link #isUseAstronomicalChatzos()} to determine the type of <em>chatzos</em> to utilize. that support it,
	 *         based on {@link #isUseAstronomicalChatzos()}.
	 * @see #getMinchaGedolaGRA()
	 * @see #getMinchaGedolaGreaterThan30(Instant)
	 * @see #getChatzosHayom()
	 * @see #isUseAstronomicalChatzos()
	 * @see #isUseAstronomicalChatzosForOtherZmanim()
	 */
	public Instant getMinchaGedola30Minutes() {
		return getTimeOffset(getChatzosHayom(), MINUTE_MILLIS * 30);
	}

	/**
	 * This method returns the time of <em>mincha gedola</em> according to the Magen Avraham with the day starting 72
	 * minutes before sunrise and ending 72 minutes after sunset. This is the earliest time to pray <em>mincha</em>. For
	 * more information on this see the documentation on {@link #getMinchaGedolaGRA() <em>mincha gedola</em>}. This is
	 * calculated as 6.5 {@link #getTemporalHour() solar hours} after <em>alos</em>. The calculation used is 6.5 *
	 * {@link #getShaahZmanis72Minutes()} after {@link #getAlos72Minutes() <em>alos</em>}. If {@link
	 * #isUseAstronomicalChatzosForOtherZmanim()} is set to <code>true</code>, the calculation will be based on 0.5
	 * {@link #getHalfDayBasedShaahZmanis(Instant, Instant) half-day based <em>sha'ah zmanis</em>} between
	 * {@link #getChatzosHayom()} and {@link #getTzais72Minutes()} after {@link #getChatzosHayom()}.
	 * 
	 * @see #getAlos72Minutes()
	 * @see #getMinchaGedolaGRA()
	 * @see #getMinchaKetanaGRA()
	 * @see #getMinchaGedolaGRA()
	 * @see #getChatzosHayom()
	 * @see #isUseAstronomicalChatzosForOtherZmanim()
	 * @return the <code>Instant</code> of the time of <em>mincha gedola</em>. If the calculation can't be computed such as
	 *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
	 *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 */
	public Instant getMinchaGedola72Minutes() {
		if (isUseAstronomicalChatzosForOtherZmanim()) {
			return getHalfDayBasedZman(getChatzosHayom(), getTzais72Minutes(), 0.5);
		} else {
			return getMinchaGedola(getAlos72Minutes(), getTzais72Minutes(), true);
		}
	}

	/**
	 * This method returns the time of <em>mincha gedola</em> according to the Magen Avraham with the day starting and
	 * ending 16.1° below the horizon. This is the earliest time to pray <em>mincha</em>. For more information on
	 * this see the documentation on {@link #getMinchaGedolaGRA() <em>mincha gedola</em>}. This is calculated as 6.5
	 * {@link #getTemporalHour() solar hours} after <em>alos</em>. The calculation used is 6.5 *
	 * {@link #getShaahZmanis16Point1Degrees()} after {@link #getAlos16Point1Degrees() <em>alos</em>}. If {@link
	 * #isUseAstronomicalChatzosForOtherZmanim()} is set to <code>true</code>, the calculation will be based on 0.5
	 * {@link #getHalfDayBasedShaahZmanis(Instant, Instant) half-day based <em>sha'ah zmanis</em>} between {@link #getChatzosHayom()}
	 * and {@link #getAlos16Point1Degrees()} after {@link #getChatzosHayom()}.
	 * @see #getShaahZmanis16Point1Degrees()
	 * @see #getMinchaGedolaGRA()
	 * @see #getMinchaKetanaGRA()
	 * @return the <code>Instant</code> of the time of <em>mincha gedola</em>. If the calculation can't be computed such as
	 *         northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle where
	 *         the sun  may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned.
	 *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 */
	public Instant getMinchaGedola16Point1Degrees() {
		if (isUseAstronomicalChatzosForOtherZmanim()) {
			return getHalfDayBasedZman(getChatzosHayom(), getTzais16Point1Degrees(), 0.5);
		} else {
			return getMinchaGedola(getAlos16Point1Degrees(), getTzais16Point1Degrees(), true);
		}
		
	}
	
	/**
	 * This method returns the time of <em>mincha gedola</em> based on the opinion of <a href=
	 * "https://en.wikipedia.org/wiki/Yaakov_Moshe_Hillel">Rabbi Yaakov Moshe Hillel</a> as published in the <em>luach</em>
	 * of the Bais Horaah of Yeshivat Chevrat Ahavat Shalom that <em>mincha gedola</em> is calculated as half a <em>shaah
	 * zmanis</em> after <em>chatzos</em> with <em>shaos zmaniyos</em> calculated based on a day starting 72 minutes before sunrise
	 * {@link #getAlos16Point1Degrees() <em>alos</em> 16.1°} and ending 13.5 minutes after sunset {@link
	 * #getTzaisGeonim3Point7Degrees() <em>tzais</em> 3.7°}. <em>Mincha gedola</em> is the earliest time to pray <em>mincha</em>.
	 * The later of this time or 30 clock minutes after <em>chatzos</em> is returned. See {@link
	 * #getMinchaGedolaGreaterThan30(Instant)} for a way to claculate the later of 30 minutes or this <em>mincha gedola</em>.
	 * For more information about <em>mincha gedola</em> see the documentation on {@link #getMinchaGedolaGRA() <em>mincha gedola</em>}.
	 * Since calculation of this <em>zman</em> involves <em>chatzos</em> that is offset from the center of the astronomical day,
	 * {@link #isUseAstronomicalChatzosForOtherZmanim()} is N/A here.
	 * @return the <code>Instant</code> of the <em>mincha gedola</em>. If the calculation can't be computed such as northern and
	 *         southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may not
	 *         reach low enough below the horizon for this calculation, a <code>null</code> will be returned. See detailed
	 *         explanation on top of the {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getAlos16Point1Degrees()
	 * @see #getTzaisGeonim3Point7Degrees()
	 * @see #getShaahZmanisAlos16Point1ToTzais3Point7()
	 * @see #getMinchaGedolaGreaterThan30(Instant)
	 */
	public Instant getMinchaGedolaAhavatShalom() {
		if (getChatzosHayom() == null || getMinchaGedola30Minutes() == null || getShaahZmanisAlos16Point1ToTzais3Point7() == Long.MIN_VALUE) {
			return null;
		} else {
			return getMinchaGedola30Minutes().compareTo(getTimeOffset(getChatzosHayom(), getShaahZmanisAlos16Point1ToTzais3Point7() / 2)) > 0 ?
					getMinchaGedola30Minutes() : getTimeOffset(getChatzosHayom(), getShaahZmanisAlos16Point1ToTzais3Point7() / 2);
		}
	}

	/**
	 * This is a convenience method that returns the later of the minchaGedola passed in and {@link
	 * #getMinchaGedola30Minutes()}. In the winter when 1/2 of a {@link #getShaahZmanisGRA() <em>shaah zmanis</em>} is less
	 * than 30 minutes {@link #getMinchaGedola30Minutes()} will be returned, otherwise the minchaGedola passed in will be
	 * returned. Since this calculation can be an offset of <em>chatzos</em> (if 30 clock minutes > 1/2 of a <em>shaah
	 * zmanis</em>), even if {@link #isUseAstronomicalChatzosForOtherZmanim()} is <code>false</code>, this <em>mincha</em>
	 * time may be affected by {@link #isUseAstronomicalChatzos()}.
	 * 
	 * @param minchaGedola
	 *            the mincha gedola to be compared to {@link #getMinchaGedola30Minutes()}.
	 * @return the <code>Instant</code> of the later of {@link #getMinchaGedolaGRA()} and {@link #getMinchaGedola30Minutes()}.
	 *         If the calculation can't be computed such as in the Arctic Circle where there is at least one day a year
	 *         where the sun does not rise, and one where it does not set, a <code>null</code> will be returned. See detailed
	 *         explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getMinchaGedolaGRA()
	 * @see #getMinchaGedola30Minutes()
	 * @see #isUseAstronomicalChatzos()
	 * 
	 */
	public Instant getMinchaGedolaGreaterThan30(Instant minchaGedola) {
		if (getMinchaGedola30Minutes() == null || minchaGedola == null) {
			return null;
		} else {
			return getMinchaGedola30Minutes().compareTo(minchaGedola) > 0 ? getMinchaGedola30Minutes()
					: minchaGedola;
		}
	}
	
	/**
	 * This is a convenience method that returns the later of {@link #getMinchaGedolaGRA()} and
	 * {@link #getMinchaGedola30Minutes()}. In the winter when 1/2 of a {@link #getShaahZmanisGRA() <em>shaah zmanis</em>} is
	 * less than 30 minutes {@link #getMinchaGedola30Minutes()} will be returned, otherwise {@link #getMinchaGedolaGRA()}
	 * will be returned. Since this calculation can be an offset of <em>chatzos</em> (if 30 clock minutes > 1/2 of a <em>shaah
	 * zmanis</em>), even if {@link #isUseAstronomicalChatzosForOtherZmanim()} is <code>false</code>, this <em>mincha</em> time
	 * may be affected by {@link #isUseAstronomicalChatzos()}.
	 * 
	 * @return the <code>Date</code> of the later of {@link #getMinchaGedolaGRA()} and {@link #getMinchaGedola30Minutes()}.
	 *         If the calculation can't be computed such as in the Arctic Circle where there is at least one day a year
	 *         where the sun does not rise, and one where it does not set, a <code>null</code> will be returned. See detailed
	 *         explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @todo Consider adjusting this to calculate the time as 30 minutes after {@link #getChatzosHayom()} that uses {@link
	 *         isUseAstronomicalChatzos()} to determine the type of <em>chatzos</em> to utilize (if the {@link
	 *         com.kosherjava.zmanim.util.AstronomicalCalculator calculator} support astronomical <em>chatzos</em>),
	 *         based on the {@link #isUseAstronomicalChatzos()} setting.
	 * @see #getMinchaGedolaGRA()
	 * @see #getMinchaGedola30Minutes()
	 * @see #getMinchaGedolaGreaterThan30(Instant)
	 * @see #isUseAstronomicalChatzos()
	 */
	public Instant getMinchaGedolaGRAGreaterThan30() {
		return getMinchaGedolaGreaterThan30(getMinchaGedolaGRA());
	}

	/**
	 * This method returns the time of <em>mincha ketana</em> according to the Magen Avraham with the day starting and
	 * ending 16.1° below the horizon. This is the preferred earliest time to pray <em>mincha</em> according to the
	 * opinion of the <a href="https://en.wikipedia.org/wiki/Maimonides">Rambam</a> and others. For more information on
	 * this see the documentation on {@link #getMinchaGedolaGRA() <em>mincha gedola</em>}. This is calculated as 9.5
	 * {@link #getTemporalHour() solar hours} after <em>alos</em>. The calculation used is 9.5 *
	 * {@link #getShaahZmanis16Point1Degrees()} after {@link #getAlos16Point1Degrees() <em>alos</em>}.
	 * 
	 * @see #getShaahZmanis16Point1Degrees()
	 * @see #getMinchaGedolaGRA()
	 * @see #getMinchaKetanaGRA()
	 * @return the <code>Instant</code> of the time of <em>mincha ketana</em>. If the calculation can't be computed such
	 *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
	 *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
	 *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 */
	public Instant getMinchaKetana16Point1Degrees() {
		return getMinchaKetana(getAlos16Point1Degrees(), getTzais16Point1Degrees(), true);
	}
	
	/**
	 * This method returns the time of <em>mincha ketana</em> based on the opinion of <a href=
	 * "https://en.wikipedia.org/wiki/Yaakov_Moshe_Hillel">Rabbi Yaakov Moshe Hillel</a> as published in the <em>luach</em>
	 * of the Bais Horaah of Yeshivat Chevrat Ahavat Shalom that <em>mincha ketana</em> is calculated as 2.5 <em>shaos
	 * zmaniyos</em> before {@link #getTzaisGeonim3Point8Degrees() <em>tzais</em> 3.8°} with <em>shaos zmaniyos</em>
	 * calculated based on a day starting at {@link #getAlos16Point1Degrees() <em>alos</em> 16.1°} and ending at
	 * <em>tzais</em> 3.8°. <em>Mincha ketana</em> is the preferred earliest time to pray <em>mincha</em> according to
	 * the opinion of the <a href="https://en.wikipedia.org/wiki/Maimonides">Rambam</a> and others. For more information
	 * on this see the documentation on {@link #getMinchaKetanaGRA() <em>mincha ketana</em>}.
	 * 
	 * @return the <code>Instant</code> of the time of <em>mincha ketana</em>. If the calculation can't be computed such as
	 *         northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle where the
	 *         sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned.
	 *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getShaahZmanisAlos16Point1ToTzais3Point8()
	 * @see #getMinchaGedolaAhavatShalom()
	 * @see #getPlagAhavatShalom()
	 */
	public Instant getMinchaKetanaAhavatShalom() {
		return getTimeOffset(getTzaisGeonim3Point8Degrees(), -getShaahZmanisAlos16Point1ToTzais3Point8() * 2.5);
	}

	/**
	 * This method returns the time of <em>mincha ketana</em> according to the Magen Avraham with the day
	 * starting 72 minutes before sunrise and ending 72 minutes after sunset. This is the preferred earliest time to pray
	 * <em>mincha</em> according to the opinion of the <a href="https://en.wikipedia.org/wiki/Maimonides">Rambam</a>
	 * and others. For more information on this see the documentation on {@link #getMinchaGedolaGRA() <em>mincha gedola</em>}.
	 * This is calculated as 9.5 {@link #getShaahZmanis72Minutes()} after <em>alos</em>. The calculation used is 9.5 *
	 * {@link #getShaahZmanis72Minutes()} after {@link #getAlos72Minutes() <em>alos</em>}.
	 * 
	 * @see #getShaahZmanis16Point1Degrees()
	 * @see #getMinchaGedolaGRA()
	 * @see #getMinchaKetanaGRA()
	 * @return the <code>Instant</code> of the time of <em>mincha ketana</em>. If the calculation can't be computed such as
	 *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
	 *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 */
	public Instant getMinchaKetana72Minutes() {
		return getMinchaKetana(getAlos72Minutes(), getTzais72Minutes(), true);
	}

	/**
	 * This method returns the time of <em>plag hamincha</em> according to the Magen Avraham with the day starting 60
	 * minutes before sunrise and ending 60 minutes after sunset. This is calculated as 10.75 hours after
	 * {@link #getAlos60Minutes() dawn}. The formula used is 10.75 {@link #getShaahZmanis60Minutes()} after {@link #getAlos60Minutes()}.
	 * 
	 * @return the <code>Instant</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
	 *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
	 *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getShaahZmanis60Minutes()
	 * @see #getAlos60Minutes()
	 * @see #getTzais60Minutes()
	 */
	public Instant getPlagHamincha60Minutes() {
		return getPlagHamincha(getAlos60Minutes(), getTzais60Minutes(), true);
	}

	/**
	 * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em> according to the
	 * Magen Avraham with the day starting 72 minutes before sunrise and ending 72 minutes after sunset. This is calculated
	 * as 10.75 hours after {@link #getAlos72Minutes() dawn}. The formula used is 10.75 {@link #getShaahZmanis72Minutes()} after
	 * {@link #getAlos72Minutes()}. Since <em>plag</em> by this calculation can occur after sunset, it should only be used
	 * <em>lechumra</em>.
	 * 
	 * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
	 *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
	 *         current plan to remove this method from the API, and this deprecation is intended to alert developers
	 *         of the danger of using it.
	 * 
	 * @return the <code>Instant</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
	 *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
	 *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getShaahZmanis72Minutes()
	 */
	@Deprecated (forRemoval=false)
	public Instant getPlagHamincha72Minutes() {
		return getPlagHamincha(getAlos72Minutes(), getTzais72Minutes(), true);
	}

	/**
	 * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em> according to the
	 * Magen Avraham with the day starting 90 minutes before sunrise and ending 90 minutes after sunset. This is calculated
	 * as 10.75 hours after {@link #getAlos90Minutes() dawn}. The formula used is 10.75 {@link #getShaahZmanis90Minutes()} after
	 * {@link #getAlos90Minutes()}. Since <em>plag</em> by this calculation can occur after sunset, it should only be used
	 * <em>lechumra</em>.
	 * 
	 * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
	 *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
	 *         current plan to remove this method from the API, and this deprecation is intended to alert developers
	 *         of the danger of using it.
	 * 
	 * @return the <code>Instant</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
	 *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
	 *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getShaahZmanis90Minutes()
	 */
	@Deprecated (forRemoval=false)
	public Instant getPlagHamincha90Minutes() {
		return getPlagHamincha(getAlos90Minutes(), getTzais90Minutes(), true);
	}

	/**
	 * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em> according to the Magen
	 * Avraham with the day starting 96 minutes before sunrise and ending 96 minutes after sunset. This is calculated as 10.75
	 * hours after {@link #getAlos96Minutes() dawn}. The formula used is 10.75 {@link #getShaahZmanis96Minutes()} after
	 * {@link #getAlos96Minutes()}. Since <em>plag</em> by this calculation can occur after sunset, it should only be used
	 * <em>lechumra</em>.
	 * 
	 * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
	 *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
	 *         current plan to remove this method from the API, and this deprecation is intended to alert developers
	 *         of the danger of using it.
	 * 
	 * @return the <code>Instant</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
	 *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
	 *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis96Minutes()
	 */
	@Deprecated (forRemoval=false)
	public Instant getPlagHamincha96Minutes() {
		return getPlagHamincha(getAlos96Minutes(), getTzais96Minutes(), true);
	}

	/**
	 * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em>. This is calculated
	 * as 10.75 hours after {@link #getAlos96Zmanis() dawn}. The formula used is 10.75 * {@link
	 * #getShaahZmanis96MinutesZmanis()} after {@link #getAlos96Zmanis() dawn}. Since <em>plag</em> by this calculation can
	 * occur after sunset, it should only be used <em>lechumra</em>.
	 * 
	 * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
	 *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
	 *         current plan to remove this method from the API, and this deprecation is intended to alert developers
	 *         of the danger of using it.
	 * 
	 * @return the <code>Instant</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
	 *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
	 *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 */
	@Deprecated (forRemoval=false)
	public Instant getPlagHamincha96MinutesZmanis() {
		return getPlagHamincha(getAlos96Zmanis(), getTzais96Zmanis(), true);
	}

	/**
	 * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em>. This is calculated
	 * as 10.75 hours after {@link #getAlos90Zmanis() dawn}. The formula used is 10.75 * {@link
	 * #getShaahZmanis90MinutesZmanis()} after {@link #getAlos90Zmanis() dawn}. Since <em>plag</em> by this calculation can
	 * occur after sunset, it should only be used <em>lechumra</em>.
	 * 
	 * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
	 *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
	 *         current plan to remove this method from the API, and this deprecation is intended to alert developers
	 *         of the danger of using it.
	 * 
	 * @return the <code>Instant</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
	 *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
	 *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 */
	@Deprecated (forRemoval=false)
	public Instant getPlagHamincha90MinutesZmanis() {
		return getPlagHamincha(getAlos90Zmanis(), getTzais90Zmanis(), true);
	}

	/**
	 * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em>. This is calculated as
	 * 10.75 hours after {@link #getAlos72Zmanis()}. The formula used is 10.75 * {@link #getShaahZmanis72MinutesZmanis()} after
	 * {@link #getAlos72Zmanis() dawn}. Since <em>plag</em> by this calculation can occur after sunset, it should only be used
	 * <em>lechumra</em>.
	 * 
	 * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
	 *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
	 *         current plan to remove this method from the API, and this deprecation is intended to alert developers
	 *         of the danger of using it.
	 * 
	 * @return the <code>Instant</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
	 *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
	 *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 */
	@Deprecated (forRemoval=false)
	public Instant getPlagHamincha72MinutesZmanis() {
		return getPlagHamincha(getAlos72Zmanis(), getTzais72Zmanis(), true);
	}

	/**
	 * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em> based on the
	 * opinion that the day starts at {@link #getAlos16Point1Degrees() <em>alos</em> 16.1°} and ends at {@link
	 * #getTzais16Point1Degrees() <em>tzais</em> 16.1°}. This is calculated as 10.75 hours <em>zmaniyos</em>
	 * after {@link #getAlos16Point1Degrees() dawn}. The formula used is 10.75 * {@link #getShaahZmanis16Point1Degrees()}
	 * after {@link #getAlos16Point1Degrees()}. Since <em>plag</em> by this calculation can occur after sunset, it
	 * should only be used <em>lechumra</em>.
	 * 
	 * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
	 *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
	 *         current plan to remove this method from the API, and this deprecation is intended to alert developers
	 *         of the danger of using it.
	 * 
	 * @return the <code>Instant</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
	 *         northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle where
	 *         the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
	 *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getShaahZmanis16Point1Degrees()
	 */
	@Deprecated (forRemoval=false)
	public Instant getPlagHamincha16Point1Degrees() {
		return getPlagHamincha(getAlos16Point1Degrees(), getTzais16Point1Degrees(), true);
	}

	/**
	 * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em> based on the
	 * opinion that the day starts at {@link #getAlos19Point8Degrees() <em>alos</em> 19.8°} and ends at {@link
	 * #getTzais19Point8Degrees() <em>tzais</em> 19.8°}. This is calculated as 10.75 hours <em>zmaniyos</em>
	 * after {@link #getAlos19Point8Degrees() dawn}. The formula used is 10.75 * {@link
	 * #getShaahZmanis19Point8Degrees()} after {@link #getAlos19Point8Degrees()}. Since <em>plag</em> by this
	 * calculation can occur after sunset, it should only be used <em>lechumra</em>.
	 * 
	 * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
	 *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
	 *         current plan to remove this method from the API, and this deprecation is intended to alert developers
	 *         of the danger of using it.
	 * 
	 * @return the <code>Instant</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
	 *         northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle where
	 *         the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
	 *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getShaahZmanis19Point8Degrees()
	 */
	@Deprecated (forRemoval=false)
	public Instant getPlagHamincha19Point8Degrees() {
		return getPlagHamincha(getAlos19Point8Degrees(), getTzais19Point8Degrees(), true);
	}

	/**
	 * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em> based on the
	 * opinion that the day starts at {@link #getAlos26Degrees() <em>alos</em> 26°} and ends at {@link
	 * #getTzais26Degrees() <em>tzais</em> 26°}. This is calculated as 10.75 hours <em>zmaniyos</em> after {@link
	 * #getAlos26Degrees() dawn}. The formula used is 10.75 * {@link #getShaahZmanis26Degrees()} after {@link
	 * #getAlos26Degrees()}. Since the <em>zman</em> based on an extremely early <em>alos</em> and a very late
	 * <em>tzais</em>, it should only be used <em>lechumra</em>.
	 * 
	 * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
	 *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
	 *         current plan to remove this method from the API, and this deprecation is intended to alert developers
	 *         of the danger of using it.
	 * 
	 * @return the <code>Instant</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
	 *         northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle where
	 *         the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
	 *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getShaahZmanis26Degrees()
	 * @see #getPlagHamincha120Minutes()
	 */
	@Deprecated (forRemoval=false)
	public Instant getPlagHamincha26Degrees() {
		return getPlagHamincha(getAlos26Degrees(), getTzais26Degrees(), true);
	}

	/**
	 * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em> based on the
	 * opinion that the day starts at {@link #getAlos18Degrees() <em>alos</em> 18°} and ends at {@link
	 * #getTzais18Degrees() <em>tzais</em> 18°}. This is calculated as 10.75 hours <em>zmaniyos</em> after {@link
	 * #getAlos18Degrees() dawn}. The formula used is 10.75 * {@link #getShaahZmanis18Degrees()} after {@link
	 * #getAlos18Degrees()}. Since <em>plag</em> by this calculation can occur after sunset, it should only be used
	 * <em>lechumra</em>.
	 * 
	 * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
	 *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
	 *         current plan to remove this method from the API, and this deprecation is intended to alert developers
	 *         of the danger of using it.
	 * 
	 * @return the <code>Instant</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
	 *         northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle where
	 *         the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
	 *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getShaahZmanis18Degrees()
	 */
	@Deprecated (forRemoval=false)
	public Instant getPlagHamincha18Degrees() {
		return getPlagHamincha(getAlos18Degrees(), getTzais18Degrees(), true);
	}

	/**
	 * This method should be used <em>lechumra</em> only and returns the time of <em>plag hamincha</em> based on the opinion that
	 * the day starts at {@link #getAlos16Point1Degrees() <em>alos</em> 16.1°} and ends at {@link #getSunset()
	 * sunset}. 10.75 <em>shaos zmaniyos</em> are calculated based on this day and added to {@link #getAlos16Point1Degrees()
	 * <em>alos</em>} to reach this time. This time is 10.75 <em>shaos zmaniyos</em> (temporal hours) after {@link
	 * #getAlos16Point1Degrees() dawn} based on the opinion that the day is calculated from a {@link #getAlos16Point1Degrees()
	 * dawn} of 16.1 degrees before sunrise to {@link #getSeaLevelSunset() sea level sunset}. This returns the time of 10.75 *
	 * the calculated <em>shaah zmanis</em> after {@link #getAlos16Point1Degrees() dawn}. Since <em>plag</em> by this
	 * calculation can occur after sunset, it should only be used <em>lechumra</em>.
	 * 
	 * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time (often after
	 *         <em>shkiah</em>), and if used <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no
	 *         current plan to remove this method from the API, and this deprecation is intended to alert developers
	 *         of the danger of using it.
	 * 
	 * @return the <code>Instant</code> of the <em>plag</em>. If the calculation can't be computed such as northern and southern
	 *         locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may not reach
	 *         low enough below the horizon for this calculation, a <code>null</code> will be returned. See detailed
	 *         explanation on top of the {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getAlos16Point1Degrees()
	 * @see #getSeaLevelSunset()
	 */
	@Deprecated (forRemoval=false)
	public Instant getPlagAlosToSunset() {
		return getPlagHamincha(getAlos16Point1Degrees(), getSunsetBasedOnElevationSetting(), false);
	}

	/**
	 * This method returns the time of <em>plag hamincha</em> based on the opinion that the day starts at
	 * {@link #getAlos16Point1Degrees() <em>alos</em> 16.1°} and ends at {@link #getTzaisGeonim7Point083Degrees()
	 * <em>tzais</em>}. 10.75 <em>shaos zmaniyos</em> are calculated based on this day and added to {@link
	 * #getAlos16Point1Degrees() <em>alos</em>} to reach this time. This time is 10.75 <em>shaos zmaniyos</em> (temporal
	 * hours) after {@link #getAlos16Point1Degrees() dawn} based on the opinion that the day is calculated from a
	 * {@link #getAlos16Point1Degrees() dawn} of 16.1 degrees before sunrise to
	 * {@link #getTzaisGeonim7Point083Degrees() <em>tzais</em>} . This returns the time of 10.75 * the calculated
	 * <em>shaah zmanis</em> after {@link #getAlos16Point1Degrees() dawn}.
	 * 
	 * @return the <code>Instant</code> of the <em>plag</em>. If the calculation can't be computed such as northern and
	 *         southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may not
	 *         reach low enough below the horizon for this calculation, a <code>null</code> will be returned. See
	 *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getAlos16Point1Degrees()
	 * @see #getTzaisGeonim7Point083Degrees()
	 */
	public Instant getPlagAlos16Point1ToTzaisGeonim7Point083Degrees() {
		return getPlagHamincha(getAlos16Point1Degrees(), getTzaisGeonim7Point083Degrees(), false);
	}
	
	/**
	 * This method returns the time of <em>plag hamincha</em> (the earliest time that Shabbos can be started) based on the
	 * opinion of <a href="https://en.wikipedia.org/wiki/Yaakov_Moshe_Hillel">Rabbi Yaakov Moshe Hillel</a> as published in
	 * the <em>luach</em> of the Bais Horaah of Yeshivat Chevrat Ahavat Shalom that that <em>plag hamincha</em> is calculated
	 * as 1.25 <em>shaos zmaniyos</em> before {@link #getTzaisGeonim3Point8Degrees() <em>tzais</em> 3.8°} with <em>shaos
	 * zmaniyos</em> calculated based on a day starting at {@link #getAlos16Point1Degrees() <em>alos</em> 16.1°} and
	 * ending at <em>tzais</em> 3.8°.
	 * 
	 * @return the <code>Instant</code> of the <em>plag</em>. If the calculation can't be computed such as northern and
	 *         southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may not
	 *         reach low enough below the horizon for this calculation, a <code>null</code> will be returned. See detailed
	 *         explanation on top of the {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getShaahZmanisAlos16Point1ToTzais3Point8()
	 * @see #getMinchaGedolaAhavatShalom()
	 * @see #getMinchaKetanaAhavatShalom()
	 */
	public Instant getPlagAhavatShalom() {
		return getTimeOffset(getTzaisGeonim3Point8Degrees(), -getShaahZmanisAlos16Point1ToTzais3Point8() * 1.25);
	}

	/**
	 * Method to return the beginning of <em>bain hashmashos</em> of Rabbeinu Tam calculated when the sun is
	 * {@link ZENITH_13_POINT_24 13.24°} below the western {@link GEOMETRIC_ZENITH geometric horizon} (90°)
	 * after sunset. This calculation is based on the same calculation of {@link #getBainHashmashosRT58Point5Minutes()
	 * <em>bain hashmashos</em> Rabbeinu Tam 58.5 minutes} but uses a degree-based calculation instead of 58.5 exact
	 * minutes. This calculation is based on the position of the sun 58.5 minutes after sunset in Jerusalem <a href=
	 * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>,
	 * which calculates to 13.24° below {@link GEOMETRIC_ZENITH geometric zenith}.
	 * NOTE: As per Yisrael Vehazmanim Vol. III page 1028, No. 50, a dip of slightly less than 13° should be used.
	 * Calculations show that the proper dip to be 13.2456° (truncated to 13.24 that provides about 1.5 second
	 * earlier (<em>lechumra</em>) time) below the horizon at that time. This makes a difference of 1 minute and 10
	 * seconds in Jerusalem during the Equinox, and 1 minute 29 seconds during the solstice as compared to the proper
	 * 13.24° versus 13°. For NY during the solstice, the difference is 1 minute 56 seconds.
	 * @todo recalculate the above based on equilux/equinox calculations.
	 * 
	 * @return the <code>Instant</code> of the sun being 13.24° below {@link GEOMETRIC_ZENITH geometric zenith}
	 *         (90°). If the calculation can't be computed such as northern and southern locations even south of the
	 *         Arctic Circle and north of the Antarctic Circle where the sun may not reach low enough below the horizon
	 *         for this calculation, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getBainHashmashosRT58Point5Minutes()
	 */
	public Instant getBainHashmashosRT13Point24Degrees() {
		return getSunsetOffsetByDegrees(ZENITH_13_POINT_24);
	}

	/**
	 * This method returns the beginning of <em>Bain hashmashos</em> of Rabbeinu Tam calculated as a 58.5-minute offset
	 * after sunset. <em>bain hashmashos</em> is 3/4 of a <a href=
	 * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> before <em>tzais</em> or 3 1/4
	 * mil after sunset. With a mil calculated as 18 minutes, 3.25 * 18 = 58.5 minutes.
	 * 
	 * @return the <code>Instant</code> of 58.5 minutes after sunset. If the calculation can't be computed such as in the
	 *         Arctic Circle where there is at least one day a year where the sun does not rise, and one where it does
	 *         not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * 
	 */
	public Instant getBainHashmashosRT58Point5Minutes() {
		return getTimeOffset(getSunsetBasedOnElevationSetting(), 58.5 * MINUTE_MILLIS);
	}

	/**
	 * This method returns the beginning of <em>bain hashmashos</em> based on the calculation of 13.5 minutes (3/4 of an
	 * 18-minute <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a>) before
	 * <em>shkiah</em> calculated as {@link #getTzaisGeonim7Point083Degrees() 7.083°}.
	 * 
	 * @return the <code>Instant</code> of the <em>bain hashmashos</em> of Rabbeinu Tam in this calculation. If the
	 *         calculation can't be computed such as northern and southern locations even south of the Arctic Circle and
	 *         north of the Antarctic Circle where the sun may not reach low enough below the horizon for this
	 *         calculation, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getTzaisGeonim7Point083Degrees()
	 */
	public Instant getBainHashmashosRT13Point5MinutesBefore7Point083Degrees() {
		return getTimeOffset(getSunsetOffsetByDegrees(ZENITH_7_POINT_083), -13.5 * MINUTE_MILLIS);
	}

	/**
	 * This method returns the beginning of <em>bain hashmashos</em> of Rabbeinu Tam calculated according to the
	 * opinion of the <em>Divrei Yosef</em> (see Yisrael Vehazmanim) calculated 5/18th (27.77%) of the time between
	 * <em>alos</em> (calculated as 19.8° before sunrise) and sunrise. This is added to sunset to arrive at the time
	 * for <em>bain hashmashos</em> of Rabbeinu Tam.
	 * 
	 * @return the <code>Instant</code> of <em>bain hashmashos</em> of Rabbeinu Tam for this calculation. If the
	 *         calculation can't be computed such as northern and southern locations even south of the Arctic Circle and
	 *         north of the Antarctic Circle where the sun may not reach low enough below the horizon for this
	 *         calculation, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 */
	public Instant getBainHashmashosRT2Stars() {
		Instant alos19Point8 = getAlos19Point8Degrees();
		Instant sunrise = getSunriseBasedOnElevationSetting();
		if (alos19Point8 == null || sunrise == null) {
			return null;
		}
		return getTimeOffset(getSunsetBasedOnElevationSetting(), (sunrise.toEpochMilli() - alos19Point8.toEpochMilli()) * (5 / 18d));
	}
	
	/**
	 * This method returns the beginning of <em>bain hashmashos</em> (twilight) according to the <a href=
	 * "https://en.wikipedia.org/wiki/Eliezer_ben_Samuel">Yereim (Rabbi Eliezer of Metz)</a> calculated as 18 minutes
	 * or 3/4 of a 24-minute <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement"
	 * >mil</a> before sunset. According to the Yereim, <em>bain hashmashos</em> starts 3/4 of a mil before sunset and
	 * <em>tzais</em> or nightfall starts at sunset.
	 * 
	 * @return the <code>Instant</code> of 18 minutes before sunset. If the calculation can't be computed such as in the
	 *         Arctic Circle where there is at least one day a year where the sun does not rise, and one where it does
	 *         not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see #getBainHashmashosYereim3Point05Degrees()
	 */
	public Instant getBainHashmashosYereim18Minutes() {
		return getTimeOffset(getSunsetBasedOnElevationSetting(), -18 * MINUTE_MILLIS);
	}
	
	/**
	 * This method returns the beginning of <em>bain hashmashos</em> (twilight) according to the <a href=
	 * "https://en.wikipedia.org/wiki/Eliezer_ben_Samuel">Yereim (Rabbi Eliezer of Metz)</a> calculated as the sun's
	 * position 3.05° above the horizon <a href=
	 * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>,
	 * its position 18 minutes or 3/4 of an 24-minute <a href=
	 * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> before sunset. According to
	 * the Yereim, <em>bain hashmashos</em> starts 3/4 of a mil before sunset and <em>tzais</em> or nightfall starts at
	 * sunset. Note that <em>lechumra</em> (of about 14 seconds) a refraction value of 0.5166° as opposed to the
	 * traditional 0.566° is used. This is more inline with the actual refraction in <em>Eretz Yisrael</em> and is
	 * brought down by <a href=
	 * "http://beinenu.com/rabbis/%D7%94%D7%A8%D7%91-%D7%99%D7%93%D7%99%D7%93%D7%99%D7%94-%D7%9E%D7%A0%D7%AA">Rabbi
	 * Yedidya Manet</a> in his <a href="https://www.nli.org.il/en/books/NNL_ALEPH002542826/NLI">Zmanei HaHalacha
	 * Lema'aseh</a> (p. 11). That is the first source that I am aware of that calculates degree-based Yereim
	 * <em>zmanim</em>. The 0.5166° refraction is also used by the <a href="https://zmanim.online/">Luach Itim
	 * Lebinah</a>. Calculating the Yereim's <em>bain hashmashos</em> using 18-minute based degrees is also suggested
	 * in the upcoming 8th edition of the zmanim Kehilchasam. For more details, see the article <a href=
	 * "https://kosherjava.com/2020/12/07/the-yereims-bein-hashmashos/">The Yereim's <em>Bain Hashmashos</em></a>.
	 * 
	 * @todo recalculate based on equinox/equilux
	 * @return the <code>Instant</code> of the sun's position 3.05° minutes before sunset. If the calculation can't
	 *         be computed such as in the Arctic Circle where there is at least one day a year where the sun does not
	 *         rise, and one where it does not set, a <code>null</code> will be returned. See detailed explanation on
	 *         top of the {@link AstronomicalCalendar} documentation.
	 * 
	 * @see ZENITH_MINUS_3_POINT_05
	 * @see #getBainHashmashosYereim18Minutes()
	 * @see #getBainHashmashosYereim2Point8Degrees()
	 * @see #getBainHashmashosYereim2Point1Degrees()
	 */
	public Instant getBainHashmashosYereim3Point05Degrees() {
		return getSunsetOffsetByDegrees(ZENITH_MINUS_3_POINT_05);
	}
	
	/**
	 * This method returns the beginning of <em>bain hashmashos</em> (twilight) according to the <a href=
	 * "https://en.wikipedia.org/wiki/Eliezer_ben_Samuel">Yereim (Rabbi Eliezer of Metz)</a> calculated as 16.875
	 * minutes or 3/4 of a 22.5-minute <a href=
	 * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> before sunset. According
	 * to the Yereim, <em>bain hashmashos</em> starts 3/4 of a mil before sunset and <em>tzais</em> or nightfall starts
	 * at sunset.
	 * 
	 * @return the <code>Instant</code> of 16.875 minutes before sunset. If the calculation can't be computed such as in the
	 *         Arctic Circle where there is at least one day a year where the sun does not rise, and one where it does
	 *         not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getBainHashmashosYereim2Point8Degrees()
	 */
	public Instant getBainHashmashosYereim16Point875Minutes() {
		return getTimeOffset(getSunsetBasedOnElevationSetting(), -16.875 * MINUTE_MILLIS);
	}
	
	/**
	 * This method returns the beginning of <em>bain hashmashos</em> (twilight) according to the <a href=
	 * "https://en.wikipedia.org/wiki/Eliezer_ben_Samuel">Yereim (Rabbi Eliezer of Metz)</a> calculated as the sun's
	 * position 2.8° above the horizon <a href=
	 * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>,
	 * its position 16.875 minutes or 3/4 of an 18-minute <a href=
	 * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> before sunset. According to
	 * the Yereim, <em>bain hashmashos</em> starts 3/4 of a mil before sunset and <em>tzais</em> or nightfall
	 * starts at sunset. Details, including how the degrees were calculated can be seen in the documentation of
	 * {@link #getBainHashmashosYereim3Point05Degrees()}.
	 * 
	 * @return the <code>Instant</code> of the sun's position 2.8° minutes before sunset. If the calculation can't
	 *         be computed such as in the Arctic Circle where there is at least one day a year where the sun does not
	 *         rise, and one where it does not set, a <code>null</code> will be returned. See detailed explanation on
	 *         top of the {@link AstronomicalCalendar} documentation.
	 * 
	 * @see ZENITH_MINUS_2_POINT_8
	 * @see #getBainHashmashosYereim16Point875Minutes()
	 * @see #getBainHashmashosYereim3Point05Degrees()
	 * @see #getBainHashmashosYereim2Point1Degrees()
	 */
	public Instant getBainHashmashosYereim2Point8Degrees() {
		return getSunsetOffsetByDegrees(ZENITH_MINUS_2_POINT_8);
	}
	
	/**
	 * This method returns the beginning of <em>bain hashmashos</em> (twilight) according to the <a href=
	 * "https://en.wikipedia.org/wiki/Eliezer_ben_Samuel">Yereim (Rabbi Eliezer of Metz)</a> calculated as 13.5 minutes
	 * or 3/4 of an 18-minute <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a>
	 * before sunset. According to the Yereim, <em>bain hashmashos</em> starts 3/4 of a mil before sunset and
	 * <em>tzais</em> or nightfall starts at sunset.
	 * 
	 * @return the <code>Instant</code> of 13.5 minutes before sunset. If the calculation can't be computed such as in the
	 *         Arctic Circle where there is at least one day a year where the sun does not rise, and one where it does
	 *         not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getBainHashmashosYereim2Point1Degrees()
	 */
	public Instant getBainHashmashosYereim13Point5Minutes() {
		return getTimeOffset(getSunsetBasedOnElevationSetting(), -13.5 * MINUTE_MILLIS);
	}
	
	/**
	 * This method returns the beginning of <em>bain hashmashos</em> according to the <a href=
	 * "https://en.wikipedia.org/wiki/Eliezer_ben_Samuel">Yereim (Rabbi Eliezer of Metz)</a> calculated as the sun's
	 * position 2.1° <b>above</b> the horizon <a href=
	 * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a> in
	 * Yerushalayim, its position 13.5 minutes or 3/4 of an 18-minute <a href=
	 * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> before sunset. According to the
	 * Yereim, <em>bain hashmashos</em> starts 3/4 of a mil before sunset and <em>tzais</em> or nightfall starts
	 * at sunset. Details, including how the degrees were calculated can be seen in the documentation of
	 * {@link #getBainHashmashosYereim3Point05Degrees()}.
	 * 
	 * @return the <code>Instant</code> of the sun's position 2.1° minutes before sunset. If the calculation can't be
	 *         computed such as in the Arctic Circle where there is at least one day a year where the sun does not rise, and
	 *         one where it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * 
	 * @see ZENITH_MINUS_2_POINT_1
	 * @see #getBainHashmashosYereim13Point5Minutes()
	 * @see #getBainHashmashosYereim2Point8Degrees()
	 * @see #getBainHashmashosYereim3Point05Degrees()
	 */
	public Instant getBainHashmashosYereim2Point1Degrees() {
		return getSunsetOffsetByDegrees(ZENITH_MINUS_2_POINT_1);
	}
	
	/**
	 * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated at the sun's
	 * position at {@link ZENITH_3_POINT_7 3.7°} below {@link GEOMETRIC_ZENITH geometric zenith} (90°), calculated
	 * as the position of the sun 13.5 minutes after sunset, the time it takes to walk 3/4 of a <a href=
	 * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> at 18 minutes a mil, or 13.5 minutes
	 *  after sunset. The sun is 3.7° below {@link GEOMETRIC_ZENITH geometric zenith} at this time in Jerusalem <a href=
	 * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>. This does
	 * not cover the 26.46 it takes to walk 49 amos (the <em>heref ayin</em> of <em>bain hashmashos</em> of Rav Yosi) at the pace
	 * of an 18-minute mil. It should be noted that Rabbi Yedidya Manet in his <a href=
	 * "https://www.nli.org.il/en/books/NNL_ALEPH002542826/NLI">Zmanei HaHalacha Lema'aseh</a> (4th edition part 2, pages and 22
	 * and 24) lists 3.65° that appears to be a drop too early.
	 * 
	 * @return the <code>Instant</code> representing the time when the sun is 3.7° below sea level.
	 * @see ZENITH_3_POINT_7
	 */
	@Deprecated (forRemoval=false)
	public Instant getTzaisGeonim3Point7Degrees() {
		return getSunsetOffsetByDegrees(ZENITH_3_POINT_7);
	}

	/**
	 * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated at the sun's
	 * position at {@link ZENITH_3_POINT_7 3.8°} below {@link GEOMETRIC_ZENITH geometric zenith} (90°), calculated
	 * as the position of the sun 13.5 minutes after sunset, the time it takes to walk 3/4 of a <a href=
	 * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> at 18 minutes a mil, plus 30 seconds
	 * for the time it takes to walk 49 amos (the <em>heref ayin</em> of <em>bain hashmashos</em> of Rav Yosi). With this being
	 * on an 18-minutes mil, 49 amos would take 26.46, rounded to 30 seconds), for a total of 14 minutes after sunset. The sun is
	 * {@link ZENITH_3_POINT_8 3.8°} below {@link GEOMETRIC_ZENITH geometric zenith} at this time in Jerusalem <a href=
	 * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>.
	 * 
	 * @return the <code>Instant</code> representing the time when the sun is 3.8° below sea level.
	 * @see ZENITH_3_POINT_8
	 */
	@Deprecated (forRemoval=false)
	public Instant getTzaisGeonim3Point8Degrees() {
		return getSunsetOffsetByDegrees(ZENITH_3_POINT_8);
	}

	/**
	 * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated at the
	 * sun's position at {@link ZENITH_5_POINT_95 5.95°} below below {@link GEOMETRIC_ZENITH geometric zenith}
	 * (90°), calculated as the position of the sun 24 minutes after sunset in Jerusalem <a href=
	 * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>. The
	 * 24 minutes is based on the Baal Hatanya's calculation of 18 minutes (3/4 of a 24 minute mil) + 4 minutes for
	 * <em>shkiah amitis</em> + 2 minutes for bain hashmashos of Rav Yosi. See Hazmanim Bahalacha vol II, ch. 50, no. 5,
	 * p. 512-513, ch. 47, and Yisrael Vehazmanim <a href="https://hebrewbooks.org/pdfpager.aspx?req=9764&st=&pgnum=266"
	 * >Vol III, ch. 13, no. 53, p. 1026</a>. Among sources he mentions for this <em>zman</em> is <a href=
	 * "https://en.wikipedia.org/wiki/Yehuda_(Leo)_Levi">Rabbi Yehuda (Leo) Levi's</a> calculations in Jewish Chrononomy
	 * and other sources. Calculations show that the time is closer to 5.93° and was seemingly rounded to 5.95°.
	 * Chabad calendars usually use the 6°-based {@link #getTzaisBaalHatanya()} that is built on this same calculation.
	 * It should be noted that Rabbi Yedidya Manet in his <a href="https://www.nli.org.il/en/books/NNL_ALEPH002542826/NLI"
	 * >Zmanei HaHalacha Lema'aseh</a> (4th edition part 2, pages and 22 and 24) lists 5.88° that appears to be a drop
	 * too early.
	 * 
	 * @return the <code>Instant</code> representing the time when the sun is 5.95° below sea level. If the calculation
	 *         can't be computed such as northern and southern locations even south of the Arctic Circle and north of
	 *         the Antarctic Circle where the sun may not reach low enough below the horizon for this calculation, a
	 *         <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
	 *         documentation.
	 * @see #getTzaisBaalHatanya()
	 */
	public Instant getTzaisGeonim5Point95Degrees() {
		return getSunsetOffsetByDegrees(ZENITH_5_POINT_95);
	}

	/**
	 * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated as 3/4
	 * of a <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> based on a
	 * 24-minute mil, or 18 minutes. It is the sun's position at {@link ZENITH_4_POINT_66 4.66°} below the
	 * western horizon. This is a very early <em>zman</em> and should not be relied on without Rabbinical guidance.
	 * This does not cover the 35.28 seconds it takes to walk 49 amos (the <em>heref ayin</em> of <em>bain hashmashos</em>
	 * of Rav Yosi) at the pace of a 24-minute mil. See {@link #getTzaisGeonim4Point8Degrees()} for a time that covers the
	 * <em>heref ayin</em>.
	 * 
	 * @return the <code>Instant</code> representing the time when the sun is 4.66° below sea level. If the calculation
	 *         can't be computed such as northern and southern locations even south of the Arctic Circle and north of
	 *         the Antarctic Circle where the sun may not reach low enough below the horizon for this calculation, a
	 *         <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
	 *         documentation.
	 * @see ZENITH_4_POINT_66
	 * @see #getTzaisGeonim4Point8Degrees()
	 */
	@Deprecated (forRemoval=false)
	public Instant getTzaisGeonim4Point66Degrees() {
		return getSunsetOffsetByDegrees(ZENITH_4_POINT_66);
	}

	/**
	 * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated as 3/4
	 * of a <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a>, based on a
	 * 22.5-minute mil, or 16 7/8 minutes. It is the sun's position at {@link ZENITH_4_POINT_42 4.42°} below the western
	 * horizon. This is a very early <em>zman</em> and should not be relied on without Rabbinical guidance. This does
	 * not cover the 33.07 seconds it takes to walk 49 amos (the <em>heref ayin</em> of <em>bain hashmashos</em> of Rav Yosi)
	 * at the pace of a 22.5 minute-mil. It should be noted that Rabbi Yedidya Manet in his <a href=
	 * "https://www.nli.org.il/en/books/NNL_ALEPH002542826/NLI">Zmanei HaHalacha Lema'aseh</a> (4th edition part 2, pages and 22
	 * and 24) lists 4.37° that appears to be a drop too early.
	 * 
	 * @return the <code>Instant</code> representing the time when the sun is 4.42° below sea level. If the calculation
	 *         can't be computed such as northern and southern locations even south of the Arctic Circle and north of
	 *         the Antarctic Circle where the sun may not reach low enough below the horizon for this calculation, a
	 *         <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
	 *         documentation.
	 * @see ZENITH_4_POINT_42
	 */
	@Deprecated (forRemoval=false)
	public Instant getTzaisGeonim4Point42Degrees() {
		return getSunsetOffsetByDegrees(ZENITH_4_POINT_42);
	}

	/**
	 * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated as the
	 * sun's position below the horizon at a time of 18.6 minutes after sunset. This is calculated as 3/4 of a 24-minute
	 * <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a>, plus 0.6 minutes for the
	 * time to walk 49 amos for <em>bain hashmashos</em> of Rav Yosi (with this <em>zman</em> based on a 24-minute mil, 49
	 * amos would take 35.28 seconds to walk), for a total of 18.6 minutes after sunset. This calculates to the sun's position
	 * at {@link ZENITH_4_POINT_8 4.8°} below the western horizon. This is based on <a href=
	 * "https://he.wikipedia.org/wiki/%D7%99%D7%97%D7%99%D7%90%D7%9C_%D7%9E%D7%99%D7%9B%D7%9C_%D7%A9%D7%9C%D7%96%D7%99%D7%A0%D7%92%D7%A8"
	 * >Rav Yechiel Michel Shlezinger's</a> <em>sefer</em> <a href="https://www.nli.org.il/he/books/NNL_ALEPH997010042055805171/NLI"
	 * >Aizehu Bain Hashmashos</a>, <a href="https://en.wikipedia.org/wiki/Yehuda_(Leo)_Levi">Rabbi Yehuda (Leo) Levi's</a>
	 * calculations in <a href="https://www.nli.org.il/en/items/NNL_ALEPH990022548970205171/NLI">Zmanei Hayom BaHalacha</a> p. 37.
	 * At this point, 3 medium sized stars are visible to a non-expert with good vision with effort. An expert knowing where to
	 * look can see the 3 medium stars as early as 15 minutes after sunset. This is explained in detail in Hazmanim Bahalacha vol
	 * II, ch. 41, no. 6 (p. 372-373, ch. 47, no. 11-12 (p. 491-493) where it is clear that medium sized stars would be visible as
	 * early as 14 minutes after sunset (13.5 minutes for 3/4 of an 18 minute Mil, plus 0.5 minutes for <em>bain Hashmashos</em>
	 * of Rav Yosi) to an expert. See more details on this earier <em>zman</em> at {@link #getTzaisGeonim3Point8Degrees()}.
	 * This is an early <em>zman</em> for <em>tzais</em>and should not be relied on without Rabbinical guidance.
	 * 
	 * @return the <code>Instant</code> representing the time when the sun is 4.8° below sea level. If the calculation
	 *         can't be computed such as northern and southern locations even south of the Arctic Circle and north of
	 *         the Antarctic Circle where the sun may not reach low enough below the horizon for this calculation, a
	 *         <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
	 *         documentation.
	 * @see ZENITH_4_POINT_8
	 */
	public Instant getTzaisGeonim4Point8Degrees() {
		return getSunsetOffsetByDegrees(ZENITH_4_POINT_8);
	}
	
	/**
	 * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> as calculated by <a href=
	 * "https://en.wikipedia.org/wiki/Yechiel_Michel_Tucazinsky">Rabbi Yechiel Michel Tucazinsky</a> as the position of
	 * the sun no later than 31 minutes after sea-level sunset in Jerusalem (the Birur halacha shows that Rav Tucazinsky's
	 * calculations for sunset, listed as 28 minutes in this case, were about 3 minutes later than reality), and at the height of
	 * the summer solstice,this <em>zman</em>, calculatons show that 30.75 minutes after <em>shkiah</em> computes to 6.45° below
	 * {@link GEOMETRIC_ZENITH geometric zenith}. This calculation is found in the <a href=
	 * "https://hebrewbooks.org/pdfpager.aspx?req=50536&st=&pgnum=51">Birur Halacha Yoreh Deah 262</a> and it is the commonly used
	 * <em>zman</em> in Israel. It is also used in the <a href="https://www.worldcat.org/oclc/243303103">Luach Itim Lebinah</a>. it
	 * should be noted that this differs from the 6.1° / 6.2° calculation for Rabbi Tucazinsky's time as calculated by the
	 * Hazmanim Bahalacha Vol II chapter 50:7 (page 515). Calculations show that 6.45° at the equinox is 26.5 minutes after
	 * <em>shkiah</em> <a href="https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox /
	 * equilux</a>. 
	 * 
	 * @return the <code>Instant</code> representing the time when the sun is 6.45° below sea level. If the
	 *         calculation can't be computed such as northern and southern locations even south of the Arctic Circle and
	 *         north of the Antarctic Circle where the sun may not reach low enough below the horizon for this
	 *         calculation, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see ZENITH_6_POINT_45
	 */
	public Instant getTzaisGeonim6Point45Degrees() {
		return getSunsetOffsetByDegrees(ZENITH_6_POINT_45);
	}

	/**
	 * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated when the
	 * sun's position {@link ZENITH_7_POINT_083 7.083° (or 7° 5\u2032}) below the western horizon. This is often
	 * referred to as 7°5' or 7° and 5 minutes. This calculation is based on the observation of 3 medium-sized
	 * stars by Dr. Baruch (Berthold) Cohn in his <em>luach</em> <a href=
	 * "https://sammlungen.ub.uni-frankfurt.de/freimann/content/titleinfo/983088">Tabellen enthaltend die Zeitangaben für
	 * den Beginn der Nacht und des Tages für die Breitengrade + 66 bis -38</a> published in Strasbourg, France in 1899.
	 * This calendar was very popular in Europe, and many other calendars based their <em>tzais</em> time on it. <a href=
	 * "https://en.wikipedia.org/wiki/David_Zvi_Hoffmann">Rav Dovid Tzvi Hoffman</a> in his
	 * <a href="https://hebrewbooks.org/1053">Sh"Ut Melamed Leho'il</a> in an exchange of letters with Baruch Cohn in <a href=
	 * "https://hebrewbooks.org/pdfpager.aspx?req=1053&st=&pgnum=37">Orach Chaim 30</a> agreed to this <em>zman</em> (page 36),
	 * as did the Sh"Ut Bnei Tziyon and the Tenuvas Sadeh. It is very close to the time of the <a href=
	 * "https://hebrewbooks.org/22044">Mekor Chesed</a> of the Sefer chasidim. It is close to the position of the sun 30 minutes
	 * after sunset in Jerusalem <a href=
	 * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>, but not
	 * Exactly. The actual position of the sun 30 minutes after sunset in Jerusalem at the equilux is 7.205° and 7.199°
	 * at the equinox. See Hazmanim Bahalacha vol 2, pages 520-521 for more details.
	 * 
	 * @return the <code>Instant</code> representing the time when the sun is 7.083° below sea level. If the
	 *         calculation can't be computed such as northern and southern locations even south of the Arctic Circle and
	 *         north of the Antarctic Circle where the sun may not reach low enough below the horizon for this
	 *         calculation, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see ZENITH_7_POINT_083
	 */
	public Instant getTzaisGeonim7Point083Degrees() {
		return getSunsetOffsetByDegrees(ZENITH_7_POINT_083);
	}
	
	/**
	 * This method returns <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated as 45 minutes
	 * after sunset during the summer solstice in New York, when the <em>neshef</em> (twilight) is the longest. The sun's
	 * position at this time computes to {@link ZENITH_7_POINT_67 7.75°} below the western horizon. See <a href=
	 * "https://hebrewbooks.org/pdfpager.aspx?req=921&pgnum=149">Igros Moshe Even Haezer 4, Ch. 4</a> (regarding
	 * <em>tzais</em> for <em>krias Shema</em>). It is also mentioned in Rabbi Heber's <a href=
	 * "https://hebrewbooks.org/53000">Shaarei Zmanim</a> on in
	 * <a href="https://hebrewbooks.org/pdfpager.aspx?req=53055&pgnum=101">chapter 10 (page 87)</a> and
	 * <a href="https://hebrewbooks.org/pdfpager.aspx?req=53055&pgnum=122">chapter 12 (page 108)</a>. Also see the
	 * time of 45 minutes in <a href="https://en.wikipedia.org/wiki/Simcha_Bunim_Cohen">Rabbi Simcha Bunim Cohen's</a> <a
	 * href="https://www.worldcat.org/oclc/179728985">The radiance of Shabbos</a> as the earliest <em>zman</em> for New York.
	 * This <em>zman</em> is also listed in the <a href="https://hebrewbooks.org/pdfpager.aspx?req=1927&pgnum=90">Divrei
	 * Shalom Vol. III, chapter 75</a>, and <a href="https://hebrewbooks.org/pdfpager.aspx?req=892&pgnum=431">Bais Av"i
	 * Vol. III, chapter 117</a>. This <em>zman</em> is also listed in the Divrei Shalom etc. chapter 177. Since this
	 * <em>zman</em> depends on the level of light, Rabbi Yaakov Shakow presented this degree-based calculation to Rabbi
	 * <a href="https://en.wikipedia.org/wiki/Shmuel_Kamenetsky">Rabbi Shmuel Kamenetsky</a> who agreed to it.
	 * @todo add hyperlinks to source of Divrei Shalom once it is located.
	 * @return the <code>Instant</code> representing the time when the sun is 7.67° below sea level. If the
	 *         calculation can't be computed such as northern and southern locations even south of the Arctic Circle and
	 *         north of the Antarctic Circle where the sun may not reach low enough below the horizon for this
	 *         calculation, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * @see ZENITH_7_POINT_67
	 */
	public Instant getTzaisGeonim7Point67Degrees() {
		return getSunsetOffsetByDegrees(ZENITH_7_POINT_67);
	}
	
	/**
	 * This method returns the <em>tzais</em> (nightfall) based on the calculations used in the <a href=
	 * "https://www.worldcat.org/oclc/243303103">Luach Itim Lebinah</a> as the stringent time for <em>tzais</em>.  It is
	 * calculated at the sun's position at {@link ZENITH_9_POINT_3 9.3°} below the western horizon.
	 * 
	 * @return the <code>Instant</code> representing the time when the sun is 9.3° below sea level. If the calculation
	 *         can't be computed such as northern and southern locations even south of the Arctic Circle and north of
	 *         the Antarctic Circle where the sun may not reach low enough below the horizon for this calculation, a
	 *         <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
	 *         documentation.
	 */
	public Instant getTzaisGeonim9Point3Degrees() {
		return getSunsetOffsetByDegrees(ZENITH_9_POINT_3);
	}
	
	/**
	 * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <em>Geonim</em> calculated as 60
	 * minutes after sunset <a href=
	 * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>, the
	 * day that a solar hour is 60 minutes in New York. The sun's position at this time computes to
	 * {@link ZENITH_9_POINT_75 9.75°} below the western horizon. This is the opinion of <a href=
	 * "https://en.wikipedia.org/wiki/Yosef_Eliyahu_Henkin">Rabbi Eliyahu Henkin</a>.  This also follows the opinion of
	 * <a href="https://en.wikipedia.org/wiki/Shmuel_Kamenetsky">Rabbi Shmuel Kamenetsky</a>. Rabbi Yaakov Shakow presented
	 * these degree-based times to Rabbi Shmuel Kamenetsky who agreed to them.
	 * 
	 * @todo recalculate based on equinox / equilux.
	 * @return the <code>Instant</code> representing the time when the sun is 9.75° below sea level. If the calculation
	 *         can't be computed such as northern and southern locations even south of the Arctic Circle and north of
	 *         the Antarctic Circle where the sun may not reach low enough below the horizon for this calculation, a
	 *         <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
	 *         documentation.
	 *
	 * @see #getTzais60Minutes()
	 */
	public Instant getTzaisGeonim9Point75Degrees() {
		return getSunsetOffsetByDegrees(ZENITH_9_POINT_75);
	}

	/**
	 * This method returns the <em>tzais</em> (nightfall) based on the opinion of the <a href=
	 * "https://en.wikipedia.org/wiki/Yair_Bacharach">Chavas Yair</a> and <a href=
	 * "https://he.wikipedia.org/wiki/%D7%9E%D7%9C%D7%9B%D7%99%D7%90%D7%9C_%D7%A6%D7%91%D7%99_%D7%98%D7%A0%D7%A0%D7%91%D7%95%D7%99%D7%9D"
	 * >Divrei Malkiel</a> that the time to walk the distance of a <a href=
	 * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> is 15 minutes, for a total of 60 minutes
	 * for 4 mil after {@link #getSunset() sunset} or {@link #getSeaLevelSunset() sea level sunset} (depending on the
	 * {@link #isUseElevation()} setting). See detailed documentation explaining the 60 minute concept at {@link #getAlos60Minutes()}.
	 * 
	 * @return the <code>Instant</code> representing 60 minutes after sea level sunset. If the calculation can't be
	 *         computed such as in the Arctic Circle where there is at least one day a year where the sun does not rise,
	 *         and one where it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getAlos60Minutes()
	 * @see #getPlagHamincha60Minutes()
	 * @see #getShaahZmanis60Minutes()
	 */
	public Instant getTzais60Minutes() {
		return getTimeOffset(getSunsetBasedOnElevationSetting(), 60 * MINUTE_MILLIS);
	}

	/**
	 * This method returns <em>tzais</em> usually calculated as 40 minutes (configurable to any offset via
	 * {@link #setAteretTorahSunsetOffset(double)}) after sunset. Please note that <em>Chacham</em> Yosef Harari-Raful
	 * of Yeshivat Ateret Torah who uses this time, does so only for calculating various other <em>zmanei hayom</em>
	 * such as <em>Sof Zman Krias Shema</em> and <em>Plag Hamincha</em>. His calendars do not publish a <em>zman</em>
	 * for <em>Tzais</em>. It should also be noted that <em>Chacham</em> Harari-Raful provided a 25 minute <em>zman</em>
	 * for Israel. This API uses 40 minutes year round in any place on the globe by default. This offset can be changed
	 *  by calling {@link #setAteretTorahSunsetOffset(double)}.
	 * 
	 * @return the <code>Instant</code> representing 40 minutes (configurable via {@link #setAteretTorahSunsetOffset})
	 *         after sea level sunset. If the calculation can't be computed such as in the Arctic Circle where there is
	 *         at least one day a year where the sun does not rise, and one where it does not set, a <code>null</code> will
	 *         be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getAteretTorahSunsetOffset()
	 * @see #setAteretTorahSunsetOffset(double)
	 */
	public Instant getTzaisAteretTorah() {
		return getTimeOffset(getSunsetBasedOnElevationSetting(), getAteretTorahSunsetOffset() * MINUTE_MILLIS);
	}

	/**
	 * Returns the offset in minutes after sunset used to calculate <em>tzais</em> based on the calculations of
	 * <em>Chacham</em> Yosef Harari-Raful of Yeshivat Ateret Torah calculations. The default value is 40 minutes.
	 * This affects most <em>zmanim</em>, since almost all zmanim use subset as part of their calculation.
	 * 
	 * @return the number of minutes after sunset for <em>Tzait</em>.
	 * @see #setAteretTorahSunsetOffset(double)
	 */
	public double getAteretTorahSunsetOffset() {
		return ateretTorahSunsetOffset;
	}

	/**
	 * Allows setting the offset in minutes after sunset for the Ateret Torah <em>zmanim</em>. The default if unset is
	 * 40 minutes. <em>Chacham</em> Yosef Harari-Raful of Yeshivat Ateret Torah uses 40 minutes globally with the exception
	 * of Israel where a 25-minute offset is used. This 40-minute (or any other) offset can be overridden by this method.
	 * This offset impacts all Ateret Torah <em>zmanim</em>.
	 * 
	 * @param ateretTorahSunsetOffset
	 *            the number of minutes after sunset to use as an offset for the Ateret Torah <em>tzais</em>
	 * @see #getAteretTorahSunsetOffset()
	 */
	public void setAteretTorahSunsetOffset(double ateretTorahSunsetOffset) {
		this.ateretTorahSunsetOffset = ateretTorahSunsetOffset;
	}

	/**
	 * This method returns the latest <em>zman krias shema</em> (time to recite Shema in the morning) based on the
	 * calculation of <em>Chacham</em> Yosef Harari-Raful of Yeshivat Ateret Torah, that the day starts
	 * {@link #getAlos72Zmanis() 1/10th of the day} before sunrise and is usually calculated as ending
	 * {@link #getTzaisAteretTorah() 40 minutes after sunset} (configurable to any offset via
	 * {@link #setAteretTorahSunsetOffset(double)}). <em>shaos zmaniyos</em> are calculated based on this day and added
	 * to {@link #getAlos72Zmanis() <em>alos</em>} to reach this time. This time is 3
	 * {@link #getShaahZmanisAteretTorah() <em>shaos zmaniyos</em>} (temporal hours) after
	 * {@link #getAlos72Zmanis() <em>alos</em> 72 <em>zmaniyos</em>}. <b>Note: </b> Based on this calculation <em>chatzos</em>
	 * will not be at midday.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em> based on this calculation. If the
	 *         calculation can't be computed such as in the Arctic Circle where there is at least one day a year where
	 *         the sun does not rise, and one where it does not set, a <code>null</code> will be returned. See detailed
	 *         explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getAlos72Zmanis()
	 * @see #getTzaisAteretTorah()
	 * @see #getAteretTorahSunsetOffset()
	 * @see #setAteretTorahSunsetOffset(double)
	 * @see #getShaahZmanisAteretTorah()
	 */
	public Instant getSofZmanShmaAteretTorah() {
		return getSofZmanShma(getAlos72Zmanis(), getTzaisAteretTorah(), false);
	}

	/**
	 * This method returns the latest <em>zman tfila</em> (time to recite the morning prayers) based on the calculation
	 * of <em>Chacham</em> Yosef Harari-Raful of Yeshivat Ateret Torah, that the day starts {@link #getAlos72Zmanis()
	 * 1/10th of the day} before sunrise and is usually calculated as ending {@link #getTzaisAteretTorah() 40 minutes
	 * after sunset} (configurable to any offset via {@link #setAteretTorahSunsetOffset(double)}). <em>shaos zmaniyos</em>
	 * are calculated based on this day and added to {@link #getAlos72Zmanis() <em>alos</em>} to reach this time. This time
	 * is 4 * {@link #getShaahZmanisAteretTorah() <em>shaos zmaniyos</em>} (temporal hours) after
	 * {@link #getAlos72Zmanis() <em>alos</em> 72 zmaniyos}.
	 * <b>Note: </b> Based on this calculation <em>chatzos</em> will not be at midday.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em> based on this calculation. If the
	 *         calculation can't be computed such as in the Arctic Circle where there is at least one day a year where
	 *         the sun does not rise, and one where it does not set, a <code>null</code> will be returned. See detailed
	 *         explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getAlos72Zmanis()
	 * @see #getTzaisAteretTorah()
	 * @see #getShaahZmanisAteretTorah()
	 * @see #setAteretTorahSunsetOffset(double)
	 */
	public Instant getSofZmanTfilaAteretTorah() {
		return getSofZmanTfila(getAlos72Zmanis(), getTzaisAteretTorah(), false);
	}

	/**
	 * This method returns the time of <em>mincha gedola</em> based on the calculation of <em>Chacham</em> Yosef
	 * Harari-Raful of Yeshivat Ateret Torah, that the day starts {@link #getAlos72Zmanis() 1/10th of the day}
	 * before sunrise and is usually calculated as ending {@link #getTzaisAteretTorah() 40 minutes after sunset}
	 * (configurable to any offset via {@link #setAteretTorahSunsetOffset(double)}). This is the preferred earliest
	 * time to pray <em>mincha</em> according to the opinion of the <a href="https://en.wikipedia.org/wiki/Maimonides"
	 * >Rambam</a> and others. For more information on this see the documentation on {@link #getMinchaGedolaGRA() <em>mincha
	 * gedola</em>}. This is calculated as 6.5 {@link #getShaahZmanisAteretTorah()  solar hours} after <em>alos</em>. The
	 * calculation used is 6.5 * {@link #getShaahZmanisAteretTorah()} after {@link #getAlos72Zmanis() <em>alos</em>}.
	 * 
	 * @see #getAlos72Zmanis()
	 * @see #getTzaisAteretTorah()
	 * @see #getShaahZmanisAteretTorah()
	 * @see #getMinchaGedolaGRA()
	 * @see #getMinchaKetanaAteretTorah()
	 * @see #getMinchaGedolaGRA()
	 * @see #getAteretTorahSunsetOffset()
	 * @see #setAteretTorahSunsetOffset(double)
	 * 
	 * @return the <code>Instant</code> of the time of <em>mincha gedola</em>. If the calculation can't be computed such as
	 *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
	 *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 */
	public Instant getMinchaGedolaAteretTorah() {
		return getMinchaGedola(getAlos72Zmanis(), getTzaisAteretTorah(), false);
	}

	/**
	 * This method returns the time of <em>mincha ketana</em> based on the calculation of
	 * <em>Chacham</em> Yosef Harari-Raful of Yeshivat Ateret Torah, that the day starts
	 * {@link #getAlos72Zmanis() 1/10th of the day} before sunrise and is usually calculated as ending
	 * {@link #getTzaisAteretTorah() 40 minutes after sunset} (configurable to any offset via
	 * {@link #setAteretTorahSunsetOffset(double)}). This is the preferred earliest time to pray <em>mincha</em>
	 * according to the opinion of the <a href="https://en.wikipedia.org/wiki/Maimonides">Rambam</a> and others.
	 * For more information on this see the documentation on {@link #getMinchaGedolaGRA() <em>mincha gedola</em>}. This is
	 * calculated as 9.5 {@link #getShaahZmanisAteretTorah() solar hours} after {@link #getAlos72Zmanis() <em>alos</em>}.
	 * The calculation used is 9.5 * {@link #getShaahZmanisAteretTorah()} after {@link #getAlos72Zmanis() <em>alos</em>}.
	 * 
	 * @see #getAlos72Zmanis()
	 * @see #getTzaisAteretTorah()
	 * @see #getShaahZmanisAteretTorah()
	 * @see #getAteretTorahSunsetOffset()
	 * @see #setAteretTorahSunsetOffset(double)
	 * @see #getMinchaGedolaGRA()
	 * @see #getMinchaKetanaGRA()
	 * @return the <code>Instant</code> of the time of <em>mincha ketana</em>. If the calculation can't be computed such as
	 *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
	 *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 */
	public Instant getMinchaKetanaAteretTorah() {
		return getMinchaKetana(getAlos72Zmanis(), getTzaisAteretTorah(), false);
	}

	/**
	 * This method returns the time of <em>plag hamincha</em> based on the calculation of <em>Chacham</em> Yosef Harari-Raful
	 * of Yeshivat Ateret Torah, that the day starts {@link #getAlos72Zmanis() 1/10th of the day} before sunrise and is
	 * usually calculated as ending {@link #getTzaisAteretTorah() 40 minutes after sunset} (configurable to any offset
	 * via {@link #setAteretTorahSunsetOffset(double)}). <em>shaos zmaniyos</em> are calculated based on this day and
	 * added to {@link #getAlos72Zmanis() <em>alos</em>} to reach this time. This time is 10.75
	 * {@link #getShaahZmanisAteretTorah() <em>shaos zmaniyos</em>} (temporal hours) after {@link #getAlos72Zmanis()
	 * dawn}.
	 * 
	 * @return the <code>Instant</code> of the <em>plag</em>. If the calculation can't be computed such as in the Arctic Circle
	 *         where there is at least one day a year where the sun does not rise, and one where it does not set, a null
	 *         will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getAlos72Zmanis()
	 * @see #getTzaisAteretTorah()
	 * @see #getShaahZmanisAteretTorah()
	 * @see #setAteretTorahSunsetOffset(double)
	 * @see #getAteretTorahSunsetOffset()
	 */
	public Instant getPlagHaminchaAteretTorah() {
		return getPlagHamincha(getAlos72Zmanis(), getTzaisAteretTorah(), false);
	}

	/**
	 * Method to return <em>tzais</em> (dusk) calculated as 72 minutes zmaniyos, or 1/10th of the day after {@link
	 * #getSeaLevelSunset() sea level sunset}. This is the way that the <a href=
	 * "https://en.wikipedia.org/wiki/Abraham_Cohen_Pimentel">Minchas Cohen</a> in Ma'amar 2:4 calculates Rebbeinu Tam's
	 * time of <em>tzeis</em>. It should be noted that this calculation results in the shortest time from sunset to
	 * <em>tzais</em> being during the winter solstice, the longest at the summer solstice and 72 clock minutes at the
	 * equinox. This does not match reality, since there is no direct relationship between the length of the day and
	 * twilight. The shortest twilight is during the equinox, the longest is during the summer solstice, and in the
	 * winter with the shortest daylight, the twilight period is longer than during the equinoxes.
	 * 
	 * @return the <code>Instant</code> representing the time. If the calculation can't be computed such as in the Arctic
	 *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
	 *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
	 *         documentation.
	 * @see #getAlos72Zmanis()
	 */
	public Instant getTzais72Zmanis() {
		return getZmanisBasedOffset(1.2);
	}

	/**
	 * Method to return <em>tzais</em> (dusk) calculated using 90 minutes zmaniyos or 1/8th of the day after {@link
	 * #getSeaLevelSunset() sea level sunset}. This time is known in Yiddish as the <em>achtel</em> (an eighth)
	 * <em>zman</em> used in various <em>kehilos</em>.
	 * 
	 * @return the <code>Instant</code> representing the time. If the calculation can't be computed such as in the Arctic
	 *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
	 *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
	 *         documentation.
	 * @see #getAlos90Zmanis()
	 */
	public Instant getTzais90Zmanis() {
		return getZmanisBasedOffset(1.5);
	}

	/**
	 * Method to return <em>tzais</em> (dusk) calculated using 96 minutes <em>zmaniyos</em> or 1/7.5 of the day after
	 * {@link #getSeaLevelSunset() sea level sunset}.
	 * 
	 * @return the <code>Instant</code> representing the time. If the calculation can't be computed such as in the Arctic
	 *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
	 *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
	 *         documentation.
	 * @see #getAlos96Zmanis()
	 */
	public Instant getTzais96Zmanis() {
		return getZmanisBasedOffset(1.6);
	}

	/**
	 * Method to return <em>tzais</em> (dusk) calculated as 90 minutes after {@link #getSunset() sunset} or {@link
	 * #getSeaLevelSunset() sea level sunset} (depending on the {@link #isUseElevation()} setting). This method returns
	 * <em>tzais</em> (nightfall) based on the opinion of the Magen Avraham that the time to walk the distance of a <a href=
	 * "https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> according to the <a href=
	 * "https://en.wikipedia.org/wiki/Maimonides">Rambam</a>'s opinion is 18 minutes, for a total of 90 minutes based on the
	 * opinion of Ula who calculated <em>tzais</em> as 5 mil after elevation adjusted <em>shkiah</em> (sunset). A similar
	 * calculation {@link #getTzais19Point8Degrees()} uses solar position* calculations based on this time.
	 * 
	 * @return the <code>Instant</code> representing the time. If the calculation can't be computed such as in the Arctic
	 *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
	 *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
	 *         documentation.
	 * @see #getTzais19Point8Degrees()
	 * @see #getAlos90Minutes()
	 */
	public Instant getTzais90Minutes() {
		return getTimeOffset(getSunsetBasedOnElevationSetting(), 90 * MINUTE_MILLIS);
	}

	/**
	 * This method should be used <em>lechumra</em> only and returns <em>tzais</em> (nightfall) based on the calculations
	 * of <a href="https://en.wikipedia.org/wiki/Avraham_Chaim_Naeh">Rav Chaim Naeh</a> that the time to walk the distance
	 * of a <a href="https://en.wikipedia.org/wiki/Biblical_and_Talmudic_units_of_measurement">mil</a> according to the <a
	 * href="https://en.wikipedia.org/wiki/Maimonides">Rambam</a>'s opinion is 2/5 of an hour (24 minutes) for a total of 120
	 * minutes based on the opinion of <em>Ula</em> who calculated <em>tzais</em> as 5 mil after {@link #getSunset()
	 * sunset} or {@link #getSeaLevelSunset() sea level sunset} (depending on the {@link #isUseElevation()} setting).
	 * A similar calculation {@link #getTzais26Degrees()} uses degree-based calculations based on this 120 minute calculation.
	 * Since the <em>zman</em> is extremely late and at a point that is long past the 18° point where the darkest point is
	 * reached, it should only be used <em>lechumra</em>, such as delaying the start of nighttime <em>mitzvos</em>.
	 * 
	 * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time, and if used
	 *         <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no current plan to remove this
	 *         method from the API, and this deprecation is intended to alert developers of the danger of using it.
	 * 
	 * @return the <code>Instant</code> representing the time. If the calculation can't be computed such as in the Arctic
	 *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
	 *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}.
	 *         documentation.
	 * @see #getTzais26Degrees()
	 * @see #getAlos120Minutes()
	 */
	@Deprecated (forRemoval=false)
	public Instant getTzais120Minutes() {
		return getTimeOffset(getSunsetBasedOnElevationSetting(), 120 * MINUTE_MILLIS);
	}

	/**
	 * This method should be used <em>lechumra</em> only and returns <em>tzais</em> (dusk) calculated using 120 minutes
	 * <em>zmaniyos</em> after {@link #getSeaLevelSunset() sea level sunset}. Since the <em>zman</em>
	 * is extremely late and at a time when the sun is well below the 18° point (scientifically the darkest point) in
	 * most places on the globe, it should only be used <em>lechumra</em>, such as delaying the start of nighttime
	 * <em>mitzvos</em>.
	 * 
	 * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time, and if used
	 *         <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no current plan to remove this
	 *         method from the API, and this deprecation is intended to alert developers of the danger of using it.
	 * 
	 * @return the <code>Instant</code> representing the time. If the calculation can't be computed such as in the Arctic
	 *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
	 *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
	 *         documentation.
	 * @see #getAlos120Zmanis()
	 * @see #getTzais120Minutes()
	 * @see #getTzais26Degrees()
	 */
	@Deprecated (forRemoval=false)
	public Instant getTzais120Zmanis() {
		return getZmanisBasedOffset(2.0);
	}

	/**
	 * This calculates the time of <em>tzais</em> at the point when the sun is 16.1° below the horizon. This is
	 * the sun's dip below the horizon 72 minutes after sunset according Rabbeinu Tam's calculation of <em>tzais</em>
	 * <a href=
	 * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a> in
	 * Jerusalem. The question of equinox VS equilux is complex, with Rabbi Meir Posen in the <a href=
	 * "https://www.worldcat.org/oclc/956316270">Ohr Meir</a> of the opinion that the equilux should be used. See
	 * Yisrael Vehazmanim vol I, 34:1:4. Rabbi Yedidya Manet in his <a href=
	 * "https://www.nli.org.il/en/books/NNL_ALEPH002542826/NLI">Zmanei HaHalacha Lema'aseh</a> (4th edition part 2, pages
	 * and 22 and 24) and Rabbi Yonah Mertzbuch (in a letter published by Rabbi Manet) are of the opinion that the
	 * astronomical equinox should be used. The difference adds up to about 9 seconds, too trivial to make much of a
	 * difference. For information on how this is calculated see the comments on {@link #getAlos16Point1Degrees()}.
	 * 
	 * @return the <code>Instant</code> representing the time. If the calculation can't be computed such as northern and
	 *         southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may
	 *         not reach low enough below the horizon for this calculation, a <code>null</code> will be returned. See
	 *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getTzais72Minutes()
	 * @see #getAlos16Point1Degrees() for more information on this calculation.
	 */
	public Instant getTzais16Point1Degrees() {
		return getSunsetOffsetByDegrees(ZENITH_16_POINT_1);
	}

	/**
	 * This method should be used <em>lechumra</em> only and returns <em>tzais</em> based on when the sun is 26°
	 * below the horizon. For information on how this is calculated see the comments on {@link #getAlos26Degrees()}.
	 * Since the <em>zman</em> is extremely late and at a point when it is long past the 18° point where the
	 * darkest point is reached, it should only be used <em>lechumra</em> such as delaying the start of nighttime
	 * <em>mitzvos</em>.
	 * 
	 * @deprecated This method should be used <em>lechumra</em> only since it returns a very late time, and if used
	 *         <em>lekula</em> can result in <em>chillul Shabbos</em> etc. There is no current plan to remove this
	 *         method from the API, and this deprecation is intended to alert developers of the danger of using it.
	 * 
	 * @return the <code>Instant</code> representing the time. If the calculation can't be computed such as northern and
	 *         southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may
	 *         not reach low enough below the horizon for this calculation, a <code>null</code> will be returned. See
	 *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getTzais120Minutes()
	 * @see #getAlos26Degrees()
	 */
	@Deprecated (forRemoval=false)
	public Instant getTzais26Degrees() {
		return getSunsetOffsetByDegrees(ZENITH_26_DEGREES);
	}

	/**
	 * For information on how this is calculated see the comments on {@link #getAlos18Degrees()}
	 * 
	 * @return the <code>Instant</code> representing the time. If the calculation can't be computed such as northern and
	 *         southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may
	 *         not reach low enough below the horizon for this calculation, a <code>null</code> will be returned. See
	 *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getAlos18Degrees()
	 */
	public Instant getTzais18Degrees() {
		return getSunsetOffsetByDegrees(ASTRONOMICAL_ZENITH);
	}

	/**
	 * For information on how this is calculated see the comments on {@link #getAlos19Point8Degrees()}.
	 * 
	 * @return the <code>Instant</code> representing the time. If the calculation can't be computed such as northern and
	 *         southern locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may
	 *         not reach low enough below the horizon for this calculation, a <code>null</code> will be returned. See
	 *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getTzais90Minutes()
	 * @see #getAlos19Point8Degrees()
	 */
	public Instant getTzais19Point8Degrees() {
		return getSunsetOffsetByDegrees(ZENITH_19_POINT_8);
	}

	/**
	 * A method to return <em>tzais</em> (dusk) calculated as 96 minutes after {@link #getSunset() sunset} or {@link
	 * #getSeaLevelSunset() sea level sunset} (depending on the {@link #isUseElevation()} setting). For information on how
	 * this is calculated see the comments on {@link #getAlos96Minutes()}.
	 * 
	 * @return the <code>Instant</code> representing the time. If the calculation can't be computed such as in the Arctic
	 *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
	 *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
	 *         documentation.
	 * @see #getAlos96Minutes()
	 */
	public Instant getTzais96Minutes() {
		return getTimeOffset(getSunsetBasedOnElevationSetting(), 96 * MINUTE_MILLIS);
	}

	/**
	 * A method that returns the local time for fixed <em>chatzos</em>. This time is noon and adjusted from
	 * standard time to account for the local latitude. The 360° of the globe divided by 24 calculates to 15°
	 * per hour with 4 minutes per degree, so at a longitude of 0 , 15, 30 etc... <em>Chatzos</em> is at exactly 12:00
	 * noon. This is the time of <em>chatzos</em> according to the <a href=
	 * "https://en.wikipedia.org/wiki/Aruch_HaShulchan">Aruch Hashulchan</a> in <a href=
	 * "https://hebrewbooks.org/pdfpager.aspx?req=7705&pgnum=426">Orach Chaim 233:14</a> and <a href=
	 * "https://en.wikipedia.org/wiki/Moshe_Feinstein">Rabbi Moshe Feinstein</a> in Igros Moshe <a href=
	 * "https://hebrewbooks.org/pdfpager.aspx?req=916&st=&pgnum=67">Orach Chaim 1:24</a> and <a href=
	 * "https://hebrewbooks.org/pdfpager.aspx?req=14675&pgnum=191">2:20</a>.
	 * Lakewood, N.J., with a longitude of -74.222, is 0.778 away from the closest multiple of 15 at -75°. This
	 * is multiplied by 4 to yield 3 minutes and 7 seconds for a <em>chatzos</em> of 11:56:53. This method is not tied
	 * to the theoretical 15° time zones, but will adjust to the actual time zone and <a
	 * href="https://en.wikipedia.org/wiki/Daylight_saving_time">Daylight saving time</a>.
	 * 
	 * @return the Instant representing the local <em>chatzos</em>
	 * @see GeoLocation#getLocalMeanTimeOffset(Instant)
	 * @see #getLocalMeanTime(LocalTime)
	 */
	public Instant getFixedLocalChatzosHayom() {
		return getLocalMeanTime(LocalTime.NOON);
	}

	/**
	 * Returns the latest time of <em>Kidush Levana</em> according to the <a
	 * href="https://en.wikipedia.org/wiki/Yaakov_ben_Moshe_Levi_Moelin">Maharil's</a> opinion that it is calculated as
	 * halfway between <em>molad</em> and <em>molad</em>. This adds half the 29 days, 12 hours and 793 chalakim time
	 * between <em>molad</em> and <em>molad</em> (14 days, 18 hours, 22 minutes and 666 milliseconds) to the month's <em>molad</em>.
	 * If the time of <em>sof zman Kiddush Levana</em> occurs during the day (between the <em>alos</em> and <em>tzais</em> passed in
	 * as parameters), it returns the <em>alos</em> passed in. If a <code>null</code> <em>alos</em> or <em>tzais</em> are passed to
	 * this method, the non-daytime adjusted time will be returned.
	 * 
	 * @param alos
	 *            the beginning of the Jewish day. If <em>Kidush Levana</em> occurs during the day (starting at <em>alos</em> and
	 *            ending at <em>tzais</em>), the time returned will be <em>alos</em>. If either the <em>alos</em> or <em>tzais</em>
	 *            parameters are null, no daytime adjustment will be made.
	 * @param tzais
	 *            the end of the Jewish day. If Kidush Levana occurs during the day (starting at <em>alos</em> and ending at
	 *            <em>tzais</em>), the time returned will be <em>alos</em>. If either the <em>alos</em> or <em>tzais</em> parameter
	 *            are null, no daytime adjustment will be made.
	 * @return the Instant representing the moment halfway between molad and molad. If the time occurs between
	 *         <em>alos</em> and <em>tzais</em>, <em>alos</em> will be returned. If the <em>zman</em> will not occur on this day, a
	 *         <code>null</code> will be returned.
	 * @see #getSofZmanKidushLevanaBetweenMoldos()
	 * @see #getSofZmanKidushLevana15Days(Instant, Instant)
	 * @see JewishCalendar#getSofZmanKidushLevanaBetweenMoldos()
	 */
	public Instant getSofZmanKidushLevanaBetweenMoldos(Instant alos, Instant tzais) {
		JewishCalendar jewishCalendar = new JewishCalendar(getLocalDate());
		
		// Do not calculate for impossible dates, but account for extreme cases. In the extreme case of Rapa Iti in French
		// Polynesia on Dec 2027 when kiddush Levana 3 days can be said on <em>Rosh Chodesh</em>, the sof zman Kiddush Levana
		// will be on the 12th of the Teves. In the case of Anadyr, Russia on Jan, 2071, sof zman Kiddush Levana between the
		// moldos will occur is on the night of 17th of Shevat. See Rabbi Dovid Heber's Shaarei Zmanim chapter 4 (pages 28 and 32).
		if (jewishCalendar.getJewishDayOfMonth() < 11 || jewishCalendar.getJewishDayOfMonth() > 16) { 
			return null;
		}
		return getMoladBasedTime(jewishCalendar.getSofZmanKidushLevanaBetweenMoldos(), alos, tzais, false);
	}
	
	/**
	 * Returns the Instant of the <em>molad</em> based time if it occurs on the current date. Since <em>Kiddush Levana</em>
	 * can only be said during the day, there are parameters to limit it to between <em>alos</em> and <em>tzais</em>. If
	 * the time occurs between <em>alos</em> and <em>tzais</em>, <em>tzais</em> will be returned.
	 * 
	 * @param moladBasedTime
	 *            the <em>molad</em> based time such as <em>molad</em>, <em>tchilas</em> and <em>sof zman Kiddush Levana</em>
	 * @param alos
	 *            optional start of day to limit <em>molad</em> times to the end of the night before or beginning of the next night.
	 *            Ignored if either <em>alos</em> or <em>tzais</em> are null.
	 * @param tzais
	 *            optional end of day to limit <em>molad</em> times to the end of the night before or beginning of the next night.
	 *            Ignored if either <em>tzais</em> or <em>alos</em> are null
	 * @param techila
	 *            is it the start of <em>Kiddush Levana</em> time or the end? If it is start roll it to the next <em>tzais</em>,
	 *            and if it is the end, return the end of the previous night (<em>alos</em> passed in). Ignored if either
	 *            <em>alos</em> or <em>tzais</em> are null.
	 * @return the <em>molad</em> based time. If the <em>zman</em> does not occur during the current date, <code>null</code> will be
	 *         returned.
	 */
	private Instant getMoladBasedTime(Instant moladBasedTime, Instant alos, Instant tzais, boolean techila) {
		Instant lastMidnight = getMidnightLastNight().toInstant();
	    Instant midnightTonight = getMidnightTonight().toInstant();
		if(moladBasedTime.isBefore(lastMidnight) || moladBasedTime.isAfter(midnightTonight)){ // Invalid time, bailout
			return null;
		} else if (alos == null || tzais == null){ // Not enough info to adjust
		   return moladBasedTime;
		} else { // It's the daytime, get the next/prev night
			if (moladBasedTime.isAfter(alos) && moladBasedTime.isBefore(tzais)) {
				if (techila) {
					return tzais;
				} else {
					return alos;
				}
			} else { // It's the night, the provided time is valid
				return moladBasedTime;
			}
		}
	}

	/**
	 * Returns the latest time of Kiddush Levana according to the <a
	 * href="https://en.wikipedia.org/wiki/Yaakov_ben_Moshe_Levi_Moelin">Maharil's</a> opinion that it is calculated as
	 * halfway between <em>molad</em> and <em>molad</em>. This adds half the 29 days, 12 hours and 793 chalakim time between
	 * <em>molad</em> and <em>molad</em> (14 days, 18 hours, 22 minutes and 666 milliseconds) to the month's <em>molad</em>.
	 * The <em>sof zman Kiddush Levana</em> will be returned even if it occurs during the day. To limit the time to between
	 * <em>tzais</em> and <em>alos</em>, see {@link #getSofZmanKidushLevanaBetweenMoldos(Instant, Instant)}.
	 * 
	 * @return the Instant representing the moment halfway between molad and molad. If the time occurs between
	 *         <em>alos</em> and <em>tzais</em>, <em>alos</em> will be returned. If the <em>zman</em> will not occur on this
	 *         day, a <code>null</code> will be returned.
	 * @see #getSofZmanKidushLevanaBetweenMoldos(Instant, Instant)
	 * @see #getSofZmanKidushLevana15Days()
	 * @see JewishCalendar#getSofZmanKidushLevanaBetweenMoldos()
	 */
	public Instant getSofZmanKidushLevanaBetweenMoldos() {
		return getSofZmanKidushLevanaBetweenMoldos(null, null); 
	}

	/**
	 * Returns the latest time of <em>Kiddush Levana</em> calculated as 15 days after the <em>molad</em>. This is the
	 * opinion brought down in the Shulchan Aruch (Orach Chaim 426). It should be noted that some opinions hold that the
	 * <a href="https://en.wikipedia.org/wiki/Moses_Isserles">Rema</a> who brings down the opinion of the <a
	 * href="https://en.wikipedia.org/wiki/Yaakov_ben_Moshe_Levi_Moelin">Maharil's</a> of calculating
	 * {@link #getSofZmanKidushLevanaBetweenMoldos(Instant, Instant) half way between <em>molad</em> and <em>molad</em>} is of
	 * the opinion that the Mechaber agrees to his opinion. Also see the Aruch Hashulchan. For additional details on the subject,
	 * see Rabbi Dovid Heber's very detailed write-up in <em>Siman Daled</em> (chapter 4) of <a href=
	 * "https://hebrewbooks.org/53000">Shaarei Zmanim</a>. If the time of <em>sof zman Kiddush Levana</em> occurs during
	 * the day (between the <em>alos</em> and <em>tzais</em> passed in as parameters), it returns the <em>alos</em> passed in. If a
	 * null <em>alos</em> or <em>tzais</em> are passed to this method, the non-daytime adjusted time will be returned.
	 * 
	 * @param alos
	 *            the beginning of the Jewish day. If <em>Kidush Levana</em> occurs during the day (starting at <em>alos</em> and
	 *            ending at <em>tzais</em>), the time returned will be <em>alos</em>. If either the <em>alos</em> or <em>tzais</em>
	 *            parameters are null, no daytime adjustment will be made.
	 * @param tzais
	 *            the end of the Jewish day. If <em>Kidush Levana</em> occurs during the day (starting at <em>alos</em> and ending at
	 *            <em>tzais</em>), the time returned will be <em>alos</em>. If either the <em>alos</em> or <em>tzais</em> parameters
	 *            are null, no daytime adjustment will be made.
	 *
	 * @return the Instant representing the moment 15 days after the molad. If the time occurs between <em>alos</em> and
	 *         <em>tzais</em>, <em>alos</em> will be returned. If the <em>zman</em> will not occur on this day, a
	 *         <code>null</code> will be returned.
	 * 
	 * @see #getSofZmanKidushLevanaBetweenMoldos(Instant, Instant)
	 * @see JewishCalendar#getSofZmanKidushLevana15Days()
	 */
	public Instant getSofZmanKidushLevana15Days(Instant alos, Instant tzais) {
		JewishCalendar jewishCalendar = new JewishCalendar(getLocalDate());
		
		// Do not calculate for impossible dates, but account for extreme cases. In the extreme case of Rapa Iti in
		// French Polynesia on Dec 2027 when kiddush Levana 3 days can be said on <em>Rosh Chodesh</em>, the sof zman Kiddush
		// Levana will be on the 12th of the Teves. in the case of Anadyr, Russia on Jan, 2071, sof zman kiddush levana will
		// occur after midnight on the 17th of Shevat. See Rabbi Dovid Heber's Shaarei Zmanim chapter 4 (pages 28 and 32).
		if (jewishCalendar.getJewishDayOfMonth() < 11 || jewishCalendar.getJewishDayOfMonth() > 17) {
			return null;
		}
		return getMoladBasedTime(jewishCalendar.getSofZmanKidushLevana15Days(), alos, tzais, false);
	}

	/**
	 * Returns the latest time of <em>Kiddush Levana</em> calculated as 15 days after the molad. This is the opinion of
	 * the Shulchan Aruch (Orach Chaim 426). It should be noted that some opinions hold that the
	 * <a href="https://en.wikipedia.org/wiki/Moses_Isserles">Rema</a> who brings down the opinion of the <a
	 * href="https://en.wikipedia.org/wiki/Yaakov_ben_Moshe_Levi_Moelin">Maharil's</a> of calculating
	 * {@link #getSofZmanKidushLevanaBetweenMoldos(Instant, Instant) half way between <em>molad</em> and <em>molad</em>} is of
	 * the opinion that the Mechaber agrees to his opinion. Also see the Aruch Hashulchan. For additional details on the subject,
	 * See Rabbi Dovid Heber's very detailed write-up in Siman Daled (chapter 4) of <a href="https://hebrewbooks.org/53000">Shaarei
	 * Zmanim</a>. The <em>sof zman Kiddush Levana</em> will be returned even if it occurs during the day. To limit the time to
	 * between <em>tzais</em> and <em>alos</em>, see {@link #getSofZmanKidushLevana15Days(Instant, Instant)}.
	 * 
	 * @return the Instant representing the moment 15 days after the <em>molad</em>. If the time occurs between
	 *         <em>alos</em> and <em>tzais</em>, <em>alos</em> will be returned. If the <em>zman</em> will not occur on this day, a
	 *         <code>null</code> will be returned.
	 * 
	 * @see #getSofZmanKidushLevana15Days(Instant, Instant)
	 * @see #getSofZmanKidushLevanaBetweenMoldos()
	 * @see JewishCalendar#getSofZmanKidushLevana15Days()
	 * 
	 */
	public Instant getSofZmanKidushLevana15Days() {
		return getSofZmanKidushLevana15Days(null, null);
	}
	
	/**
	 * Returns the earliest time of <em>Kiddush Levana</em> according to <a href=
	 * "https://en.wikipedia.org/wiki/Yonah_Gerondi">Rabbeinu Yonah</a>'s opinion that it can be said 3 days after the
	 * <em>molad</em>. The time will be returned even if it occurs during the day when <em>Kiddush Levana</em> can't be said.
	 * Use {@link #getTchilasZmanKidushLevana3Days(Instant, Instant)} if you want to limit the time to night hours.
	 * 
	 * @return the Instant representing the moment 3 days after the molad. If the <em>zman</em> will not occur on this day, a
	 *         <code>null</code> will be returned.
	 * @see #getTchilasZmanKidushLevana3Days(Instant, Instant)
	 * @see #getTchilasZmanKidushLevana7Days()
	 * @see JewishCalendar#getTchilasZmanKidushLevana3Days()
	 */
	public Instant getTchilasZmanKidushLevana3Days() {
		return getTchilasZmanKidushLevana3Days(null, null);
	}

	/**
	 * Returns the earliest time of <em>Kiddush Levana</em> according to <a href=
	 * "https://en.wikipedia.org/wiki/Yonah_Gerondi">Rabbeinu Yonah</a>'s opinion that it can be said 3 days after the <em>molad</em>.
	 * If the time of <em>tchilas zman Kiddush Levana</em> occurs during the day (between <em>alos</em> and <em>tzais</em> passed to
	 * this method) it will return the following <em>tzais</em>. If null is passed for either <em>alos</em> or <em>tzais</em>, the
	 * actual <em>tchilas zman Kiddush Levana</em> will be returned, regardless of if it is during the day or not.
	 * 
	 * @param alos
	 *            the beginning of the Jewish day. If Kidush Levana occurs during the day (starting at <em>alos</em> and ending at
	 *            <em>tzais</em>), the time returned will be <em>tzais</em>. If either the <em>alos</em> or <em>tzais</em> parameters
	 *            are null, no daytime adjustment will be made.
	 * @param tzais
	 *            the end of the Jewish day. If <em>Kidush Levana</em> occurs during the day (starting at <em>alos</em> and ending at
	 *            <em>tzais</em>), the time returned will be <em>tzais</em>. If either the <em>alos</em> or <em>tzais</em> parameters
	 *            are null, no daytime adjustment will be made.
	 *
	 * @return the Instant representing the moment 3 days after the molad. If the time occurs between <em>alos</em> and
	 *         <em>tzais</em>, <em>tzais</em> will be returned. If the <em>zman</em> will not occur on this day, a
	 *         <code>null</code> will be returned.
	 * @see #getTchilasZmanKidushLevana3Days()
	 * @see #getTchilasZmanKidushLevana7Days(Instant, Instant)
	 * @see JewishCalendar#getTchilasZmanKidushLevana3Days()
	 */
	public Instant getTchilasZmanKidushLevana3Days(Instant alos, Instant tzais) {
		JewishCalendar jewishCalendar = new JewishCalendar(getLocalDate());
		
		// Do not calculate for impossible dates, but account for extreme cases. Tchilas zman kiddush Levana 3 days for
		// the extreme case of Rapa Iti in French Polynesia on Dec 2027 when kiddush Levana 3 days can be said on the evening
		// of the 30th, the second night of Rosh Chodesh. The 3rd day after the <em>molad</em> will be on the 4th of the month.
		// In the case of Anadyr, Russia on Jan, 2071, when sof zman kiddush levana is on the 17th of the month, the 3rd day
		// from the molad will be on the 5th day of Shevat. See Rabbi Dovid Heber's Shaarei Zmanim chapter 4 (pages 28 and 32).
		if (jewishCalendar.getJewishDayOfMonth() > 5 && jewishCalendar.getJewishDayOfMonth() < 30) {
			return null;
		}
		
		Instant zman = getMoladBasedTime(jewishCalendar.getTchilasZmanKidushLevana3Days(), alos, tzais, true);
		
		// Get the following month's zman kiddush Levana for the extreme case of Rapa Iti in French Polynesia on Dec 2027 when kiddush
		// Levana can be said on Rosh Chodesh (the evening of the 30th). See Rabbi Dovid Heber's Shaarei Zmanim chapter 4 (page 32)
		if (zman == null && jewishCalendar.getJewishDayOfMonth() == 30) {
			jewishCalendar.plusMonths(1);
			zman = getMoladBasedTime(jewishCalendar.getTchilasZmanKidushLevana3Days(), null, null, true);
		}
		
		return zman;
	}
	
	/**
	 * Returns the point in time of <em>Molad</em> as a <code>Instant</code> Object. For the traditional day of week, hour,
	 * minute and chalakim, {@link JewishCalendar#getMoladAsInstant()} and the not yet completed
	 * {@link com.kosherjava.zmanim.hebrewcalendar.HebrewDateFormatter} that will have formatting for this.
	 * 
	 * @return the Instant representing the moment of the molad. If the <em>molad</em> does not occur on this day, a
	 *         <code>null</code> will be returned.
	 * 
	 * @see #getTchilasZmanKidushLevana3Days()
	 * @see #getTchilasZmanKidushLevana7Days(Instant, Instant)
	 * @see JewishCalendar#getMoladAsInstant()
	 */
	public Instant getZmanMolad() {
		JewishCalendar jewishCalendar = new JewishCalendar(getLocalDate());
		
		// Optimize to not calculate for impossible dates, but account for extreme cases. The molad in the extreme case of Rapa
		// Iti in French Polynesia on Dec 2027 occurs on the night of the 27th of Kislev. In the case of Anadyr, Russia on
		// Jan 2071, the molad will be on the 2nd day of Shevat. See Rabbi Dovid Heber's Shaarei Zmanim chapter 4 (pages 28 and 32).
		if (jewishCalendar.getJewishDayOfMonth() > 2 && jewishCalendar.getJewishDayOfMonth() < 27) {
			return null;
		}
		Instant molad = getMoladBasedTime(jewishCalendar.getMoladAsInstant(), null, null, true);

		// deal with molad that happens on the end of the previous month
		if (molad == null && jewishCalendar.getJewishDayOfMonth() > 26) {
			jewishCalendar.plusMonths(1);
			molad = getMoladBasedTime(jewishCalendar.getMoladAsInstant(), null, null, true);
		}
		return molad;
	}

	/**
	 * Returns the earliest time of <em>Kiddush Levana</em> according to the opinions that it should not be said until 7
	 * days after the <em>molad</em>. If the time of <em>tchilas zman Kiddush Levana</em> occurs during the day (between
	 * {@link #getAlos72Minutes() <em>alos</em>} and {@link #getTzais72Minutes() <em>tzais</em>}) it
	 * return the next <em>tzais</em>.
	 * 
	 * @param alos
	 *            the beginning of the Jewish day. If <em>Kidush Levana</em> occurs during the day (starting at <em>alos</em>
	 *            and ending at <em>tzais</em>), the time returned will be <em>tzais</em>. If either the <em>alos</em> or
	 *            <em>tzais</em> parameters are null, no daytime adjustment will be made.
	 * @param tzais
	 *            the end of the Jewish day. If <em>Kidush Levana</em> occurs during the day (starting at <em>alos</em> and
	 *            ending at <em>tzais</em>), the time returned will be <em>tzais</em>. If either the <em>alos</em> or
	 *            <em>tzais</em> parameters are null, no daytime adjustment will be made.
	 *
	 * @return the Instant representing the moment 7 days after the molad. If the time occurs between <em>alos</em> and
	 *         <em>tzais</em>, <em>tzais</em> will be returned. If the <em>zman</em> will not occur on this day, a
	 *         <code>null</code> will be returned.
	 * @see #getTchilasZmanKidushLevana3Days(Instant, Instant)
	 * @see #getTchilasZmanKidushLevana7Days()
	 * @see JewishCalendar#getTchilasZmanKidushLevana7Days()
	 */
	public Instant getTchilasZmanKidushLevana7Days(Instant alos, Instant tzais) {
		JewishCalendar jewishCalendar = new JewishCalendar(getLocalDate());
		
		// Optimize to not calculate for impossible dates, but account for extreme cases. Tchilas zman kiddush Levana 7 days for
		// the extreme case of Rapa Iti in French Polynesia on Jan 2028 (when kiddush Levana 3 days can be said on the evening
		// of the 30th, the second night of Rosh Chodesh), the 7th day after the molad will be on the 4th of the month.
		// In the case of Anadyr, Russia on Jan, 2071, when sof zman kiddush levana is on the 17th of the month, the 7th day
		// from the molad will be on the 9th day of Shevat. See Rabbi Dovid Heber's Shaarei Zmanim chapter 4 (pages 28 and 32).
		if (jewishCalendar.getJewishDayOfMonth() < 4 || jewishCalendar.getJewishDayOfMonth() > 9) { 
			return null;
		}
		
		return getMoladBasedTime(jewishCalendar.getTchilasZmanKidushLevana7Days(), alos, tzais, true);
	}

	/**
	 * Returns the earliest time of <em>Kiddush Levana</em> according to the opinions that it should not be said until 7
	 * days after the <em>molad</em>. The time will be returned even if it occurs during the day when <em>Kiddush Levana</em>
	 * can't be recited. Use {@link #getTchilasZmanKidushLevana7Days(Instant, Instant)} if you want to limit the time to night hours.
	 * 
	 * @return the Instant representing the moment 7 days after the molad regardless of it is day or night. If the <em>zman</em>
	 *         will not occur on this day, a <code>null</code> will be returned.
	 * @see #getTchilasZmanKidushLevana7Days(Instant, Instant)
	 * @see JewishCalendar#getTchilasZmanKidushLevana7Days()
	 * @see #getTchilasZmanKidushLevana3Days()
	 */
	public Instant getTchilasZmanKidushLevana7Days() {
		return getTchilasZmanKidushLevana7Days(null, null);
	}

	/**
	 * This method returns the latest time one is allowed eating <em>chametz</em> on <em>Erev Pesach</em> according to
	 * the opinion of the <a href="https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a>. This time is identical to the {@link
	 * #getSofZmanTfilaGRA() <em>Sof zman tfilah</em> GRA} and is provided as a convenience method for those who are
	 * unaware how this <em>zman</em> is calculated. This time is 4 hours into the day based on the opinion of the
	 * <a href="https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a> that the day is calculated from sunrise to sunset.
	 * This returns the time 4 * {@link #getShaahZmanisGRA()} after {@link #getSeaLevelSunrise() sea level sunrise}. If it
	 * is not <em>erev Pesach</em>, a <code>null</code> will be returned.
	 * @return the <code>Instant</code> one is allowed eating <em>chametz</em> on <em>Erev Pesach</em>. If it is not <em>erev
	 *         Pesach</em> or the calculation can't be computed such as in the Arctic Circle where there is at least one
	 *         day a year where the sun does not rise, and one where it does not set, a <code>null</code> will be returned.
	 *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanisGRA()
	 * @see #getSofZmanTfilaGRA()
	 * @see #getSofZmanAchilasChametz(Instant, Instant, boolean)
	 */
	public Instant getSofZmanAchilasChametzGRA() {
		return getSofZmanAchilasChametz(getSunriseBasedOnElevationSetting(), getSunsetBasedOnElevationSetting(), true);
	}

	/**
	 * This method returns the latest time one is allowed eating <em>chametz</em> on <em>Erev Pesach</em> according to the
	 * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em>
	 * being {@link #getAlos72Minutes() 72} minutes before {@link #getSunset() sunrise}. This time is identical to the
	 * {@link #getSofZmanTfilaMGA72Minutes() <em>Sof zman tfilah</em> MGA 72 minutes}. This time is 4 {@link
	 * #getShaahZmanis72Minutes() <em>shaos zmaniyos</em>} (temporal hours) after {@link #getAlos72Minutes() dawn} based on the
	 * opinion of the MGA that the day is calculated from a {@link #getAlos72Minutes() dawn} of 72 minutes before sunrise to {@link
	 * #getTzais72Minutes() nightfall} of 72 minutes after sunset. This returns the time of 4 * {@link #getShaahZmanis72Minutes()}
	 * after {@link #getAlos72Minutes() dawn}. If it is not <em>erev Pesach</em>, a <code>null</code> will be returned.
	 * 
	 * @return the <code>Instant</code> of the latest time of eating <em>chametz</em>. If it is not <em>erev Pesach</em> or the
	 *         calculation can't be computed such as in the Arctic Circle where there is at least one day a year where the sun does
	 *         not rise, and one where it does not set, a <code>null</code> will be returned. See detailed explanation on top of
	 *         the {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis72Minutes()
	 * @see #getAlos72Minutes()
	 * @see #getSofZmanTfilaMGA72Minutes()
	 * @see #getSofZmanAchilasChametz(Instant, Instant, boolean)
	 */
	public Instant getSofZmanAchilasChametzMGA72Minutes() {
		return getSofZmanAchilasChametz(getAlos72Minutes(), getTzais72Minutes(), true);
	}
	
	/**
	 * This method returns the latest time one is allowed eating <em>chametz</em> on <em>Erev Pesach</em> according to the opinion
	 * of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
	 * #getAlos72Zmanis() 72 zmaniyos} minutes before {@link #getSunset() sunrise}. This time is identical to the
	 * {@link #getSofZmanTfilaMGA72MinutesZmanis() <em>Sof zman tfilah</em> MGA 72 minutes zmanis}. This time is 4 {@link
	 * #getShaahZmanis72MinutesZmanis() <em>shaos zmaniyos</em>} (temporal hours) after {@link #getAlos72Minutes() dawn} based on the
	 * opinion of the MGA that the day is calculated from a {@link #getAlos72Zmanis() dawn} of 72 minutes zmanis before sunrise to
	 * {@link #getTzais72Zmanis() nightfall} of 72 minutes zmanis after sunset. This returns the time of 4 * {@link
	 * #getShaahZmanis72MinutesZmanis()} after {@link #getAlos72Zmanis() dawn}. If it is not <em>erev Pesach</em>, a <code>null</code>
	 * will be
	 * returned.
	 *
	 * @return the <code>Instant</code> of the latest time of eating <em>chametz</em>. If it is not <em>erev Pesach</em> or the
	 *         calculation can't be computed such as in the Arctic Circle where there is at least one day a year where the sun does
	 *         not rise, and one where it does not set, a <code>null</code> will be returned. See detailed explanation on top of
	 *         the {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis72MinutesZmanis()
	 * @see #getAlos72Zmanis()
	 * @see #getSofZmanTfilaMGA72MinutesZmanis()
	 * @see #getSofZmanAchilasChametz(Instant, Instant, boolean)
	 */
	public Instant getSofZmanAchilasChametzMGA72MinutesZmanis() {
		return getSofZmanAchilasChametz(getAlos72Zmanis(), getTzais72Zmanis(), true);
	}

	/**
	 * This method returns the latest time one is allowed eating <em>chametz</em> on <em>Erev Pesach</em> according to the
	 * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em>
	 * being {@link #getAlos16Point1Degrees() 16.1°} before {@link #getSunset() sunrise}. This time is 4 {@link
	 * #getShaahZmanis16Point1Degrees() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos16Point1Degrees() dawn} based
	 * on the opinion of the MGA that the day is calculated from dawn to nightfall with both being 16.1° below sunrise or
	 * sunset. This returns the time of 4 {@link #getShaahZmanis16Point1Degrees()} after {@link #getAlos16Point1Degrees() dawn}.
	 * If it is not <em>erev Pesach</em>, a <code>null</code> will be returned.
	 * 
	 * @return the <code>Instant</code> of the latest time of eating <em>chametz</em>. If it is not <em>erev Pesach</em> or the
	 *         calculation can't be computed such as northern and southern locations even south of the Arctic Circle and north of
	 *         the Antarctic Circle where the sun may not reach low enough below the horizon for this calculation, a
	 *         <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis16Point1Degrees()
	 * @see #getAlos16Point1Degrees()
	 * @see #getSofZmanTfilaMGA16Point1Degrees()
	 * @see #getSofZmanAchilasChametz(Instant, Instant, boolean)
	 */
	public Instant getSofZmanAchilasChametzMGA16Point1Degrees() {
		return getSofZmanAchilasChametz(getAlos16Point1Degrees(), getTzais16Point1Degrees(), true);
	}

	/**
	 * This method returns the latest time for burning <em>chametz</em> on <em>Erev Pesach</em> according to the opinion
	 * of the <a href="https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a>. This time is 5 hours into the day based on the
	 * opinion of the <a href="https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a> that the day is calculated from
	 * sunrise to sunset. This returns the time 5 * {@link #getShaahZmanisGRA()} after {@link #getSeaLevelSunrise() sea
	 * level sunrise}. If it is not  <em>erev Pesach</em>, a <code>null</code> will be returned.
	 * @return the <code>Instant</code> of the latest time for burning <em>chametz</em> on <em>Erev Pesach</em>. If it is not
	 *         <em>erev Pesach</em> or the calculation can't be computed such as in the Arctic Circle where there is at least
	 *         one day a year where the sun does not rise, and one where it does not set, a <code>null</code> will be
	 *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanisGRA()
	 * @see #getSofZmanBiurChametz(Instant, Instant, boolean)
	 */
	public Instant getSofZmanBiurChametzGRA() {
		return getSofZmanBiurChametz(getSunriseBasedOnElevationSetting(), getSunsetBasedOnElevationSetting(), true);
	}

	/**
	 * This method returns the latest time for burning <em>chametz</em> on <em>Erev Pesach</em> according to the opinion of the
	 * <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
	 * #getAlos72Minutes() 72} minutes before {@link #getSunset() sunrise}. This time is 5 {@link
	 * #getShaahZmanis72Minutes() <em>shaos zmaniyos</em>} (temporal hours) after {@link #getAlos72Minutes() dawn} based on the
	 * opinion of the MGA that the day is calculated from a {@link #getAlos72Minutes() dawn} of 72 minutes before sunrise to {@link
	 * #getTzais72Minutes() nightfall} of 72 minutes after sunset. This returns the time of 5 * {@link #getShaahZmanis72Minutes()}
	 * after {@link #getAlos72Minutes() dawn}. If it is not  <em>erev Pesach</em>, a <code>null</code> will be returned.
	 * @return the <code>Instant</code> of the latest time for burning <em>chametz</em> on <em>Erev Pesach</em>. If it is not
	 *         <em>erev Pesach</em> or the calculation can't be computed such as in the Arctic Circle where there is at
	 *         least one day a year where the sun does not rise, and one where it does not set, a <code>null</code> will be
	 *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis72Minutes()
	 * @see #getAlos72Minutes()
	 * @see #getSofZmanBiurChametz(Instant, Instant, boolean)
	 */
	public Instant getSofZmanBiurChametzMGA72Minutes() {
		return getSofZmanBiurChametz(getAlos72Minutes(), getTzais72Minutes(), true);
	}
	
	/**
	 * This method returns the latest time for burning <em>chametz</em> on <em>Erev Pesach</em> according to the opinion of the
	 * <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em> being {@link
	 * #getAlos72Zmanis() 72} minutes zmanis before {@link #getSunset() sunrise}. This time is 5 {@link
	 * #getShaahZmanis72MinutesZmanis() <em>shaos zmaniyos</em>} (temporal hours) after {@link #getAlos72Zmanis() dawn} based on the
	 * opinion of the MGA that the day is calculated from a {@link #getAlos72Zmanis() dawn} of 72 minutes zmanis before sunrise to
	 * {@link #getTzais72Zmanis() nightfall} of 72 minutes zmanis after sunset. This returns the time of 5 * {@link
	 * #getShaahZmanis72MinutesZmanis()} after {@link #getAlos72Zmanis() dawn}. If it is not  <em>erev Pesach</em>, a <code>null</code>
	 * will be
	 * returned.
	 * @return the <code>Instant</code> of the latest time for burning <em>chametz</em> on <em>Erev Pesach</em>. If it is not
	 *         <em>erev Pesach</em> or the calculation can't be computed such as in the Arctic Circle where there is at
	 *         least one day a year where the sun does not rise, and one where it does not set, a <code>null</code> will be
	 *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanis72MinutesZmanis()
	 * @see #getAlos72Zmanis()
	 * @see #getSofZmanBiurChametz(Instant, Instant, boolean)
	 */
	public Instant getSofZmanBiurChametzMGA72MinutesZmanis() {
		return getSofZmanBiurChametz(getAlos72Zmanis(), getTzais72Zmanis(), true);
	}

	/**
	 * This method returns the latest time for burning <em>chametz</em> on <em>Erev Pesach</em> according to the opinion
	 * of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> based on <em>alos</em>
	 * being {@link #getAlos16Point1Degrees() 16.1°} before {@link #getSunset() sunrise}. This time is 5
	 * {@link #getShaahZmanis16Point1Degrees() <em>shaos zmaniyos</em>} (solar hours) after {@link #getAlos16Point1Degrees()
	 * dawn} based on the opinion of the MGA that the day is calculated from dawn to nightfall with both being 16.1°
	 * below sunrise or sunset. This returns the time of 5 {@link #getShaahZmanis16Point1Degrees()} after
	 * {@link #getAlos16Point1Degrees() dawn}. If it is not  <em>erev Pesach</em>, a <code>null</code> will be returned.
	 * @return the <code>Instant</code> of the latest time for burning <em>chametz</em> on <em>Erev Pesach</em>. If it is not
	 *         <em>erev Pesach</em> or the calculation can't be computed such as northern and southern locations even south
	 *         of the Arctic Circle and north of the Antarctic Circle where the sun may not reach low enough below the
	 *         horizon for this calculation, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getShaahZmanis16Point1Degrees()
	 * @see #getAlos16Point1Degrees()
	 * @see #getSofZmanBiurChametz(Instant, Instant, boolean)
	 */
	public Instant getSofZmanBiurChametzMGA16Point1Degrees() {
		return getSofZmanBiurChametz(getAlos16Point1Degrees(), getTzais16Point1Degrees(), true);
	}

	/**
	 * A method that returns the <a href="https://en.wikipedia.org/wiki/Shneur_Zalman_of_Liadi">Baal Hatanya</a>'s
	 * a <em>shaah zmanis</em> ({@link #getTemporalHour(Instant, Instant) temporal hour}). This forms the base for the
	 * Baal Hatanya's  day  based calculations that are calculated as a 1.583° dip below the horizon after sunset.
	 * According to the Baal Hatanya, <em>shkiah amiti</em>, true (halachic) sunset, is when the top of the 
	 * sun's disk disappears from view at an elevation similar to the mountains of Eretz Yisrael.
	 * This time is calculated as the point at which the center of the sun's disk is 1.583 degrees below the horizon.
	 * A method that returns a <em>shaah zmanis</em> ({@link #getTemporalHour(Instant, Instant) temporal hour}) calculated 
	 * based on the <a href="https://en.wikipedia.org/wiki/Shneur_Zalman_of_Liadi">Baal Hatanya</a>'s <em>netz
	 * amiti</em> and <em>shkiah amiti</em> using a dip of 1.583° below the sea level horizon. This calculation divides
	 * the day based on the opinion of the Baal Hatanya that the day runs from {@link #getSunriseBaalHatanya() netz amiti}
	 * to {@link #getSunsetBaalHatanya() <em>shkiah amiti</em>}. The calculations are based on a day from {@link
	 * #getSunriseBaalHatanya() sea level <em>netz amiti</em>} to {@link #getSunsetBaalHatanya() sea level <em>shkiah amiti</em>}.
	 * The day is split into 12 equal parts with each one being a <em>shaah zmanis</em>. This method is similar to {@link
	 * #getTemporalHour}, but all calculations are based on a sea level sunrise and sunset.
	 * @return the <code>long</code> millisecond length of a <em>shaah zmanis</em> calculated from
	 *         {@link #getSunriseBaalHatanya() <em>netz amiti</em> (sunrise)} to {@link #getSunsetBaalHatanya() <em>shkiah amiti</em>
	 *         ("real" sunset)}. If the calculation can't be computed such as in the Arctic Circle where there is at least one day a
	 *         year where the sun does not rise, and one where it does not set, {@link Long#MIN_VALUE} will be returned. See
	 *         detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getTemporalHour(Instant, Instant)
	 * @see #getSunriseBaalHatanya()
	 * @see #getSunsetBaalHatanya()
	 * @see ZENITH_1_POINT_583
	 */
	public long getShaahZmanisBaalHatanya() {
		return getTemporalHour(getSunriseBaalHatanya(), getSunsetBaalHatanya());
	}

	/**
	 * Returns the <a href="https://en.wikipedia.org/wiki/Shneur_Zalman_of_Liadi">Baal Hatanya</a>'s <em>alos</em>
	 * (dawn) calculated as the time when the sun is 16.9° below the eastern {@link GEOMETRIC_ZENITH geometric horizon}
	 * before {@link #getSunset() sunrise}. It is based on the calculation that the time between dawn and
	 * <em>netz amiti</em> (sunrise) is 72 minutes, the time that is takes to walk 4 mil at 18 minutes
	 * a mil (<a href="https://en.wikipedia.org/wiki/Maimonides">Rambam</a> and others). The sun's position at 72
	 * minutes before {@link #getSunriseBaalHatanya <em>netz amiti</em> (sunrise)} in Jerusalem <a href=
	 * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a> is
	 * 16.9° below {@link GEOMETRIC_ZENITH geometric zenith}.
	 * 
	 * @return The <code>Instant</code> of dawn. If the calculation can't be computed such as northern and southern
	 *         locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may not reach
	 *         low enough below the horizon for this calculation, a <code>null</code> will be returned. See detailed
	 *         explanation on top of the {@link AstronomicalCalendar} documentation.
	 */
	public Instant getAlosBaalHatanya() {
		return getSunriseOffsetByDegrees(ZENITH_16_POINT_9);
	}

	/**
	 * This method returns the latest <em>zman krias shema</em> (time to recite Shema in the morning). This time is 3
	 * {@link #getShaahZmanisBaalHatanya() <em>shaos zmaniyos</em>} (solar hours) after {@link #getSunriseBaalHatanya() 
	 * <em>netz amiti</em> (sunrise)} based on the opinion of the Baal Hatanya that the day is calculated from
	 * sunrise to sunset. This returns the time 3 * {@link #getShaahZmanisBaalHatanya()} after {@link #getSunriseBaalHatanya() 
	 * <em>netz amiti</em> (sunrise)}.
	 * 
	 * @see #getSofZmanShma(Instant, Instant)
	 * @see #getShaahZmanisBaalHatanya()
	 * @return the <code>Instant</code> of the latest <em>zman shema</em> according to the Baal Hatanya. If the calculation
	 *         can't be computed such as in the Arctic Circle where there is at least one day a year where the sun does
	 *         not rise, and one where it does not set, a <code>null</code> will be returned. See detailed explanation on
	 *         top of the {@link AstronomicalCalendar} documentation.
	 */
	public Instant getSofZmanShmaBaalHatanya() {
		return getSofZmanShma(getSunriseBaalHatanya(), getSunsetBaalHatanya(), true);
	}

	/**
	 * This method returns the latest <em>zman tfilah</em> (time to recite the morning prayers). This time is 4
	 * hours into the day based on the opinion of the Baal Hatanya that the day is
	 * calculated from sunrise to sunset. This returns the time 4 * {@link #getShaahZmanisBaalHatanya()} after
	 * {@link #getSunriseBaalHatanya() <em>netz amiti</em> (sunrise)}.
	 * 
	 * @see #getSofZmanTfila(Instant, Instant)
	 * @see #getShaahZmanisBaalHatanya()
	 * @return the <code>Instant</code> of the latest <em>zman tfilah</em>. If the calculation can't be computed such as in
	 *         the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it does
	 *         not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 */
	public Instant getSofZmanTfilaBaalHatanya() {
		return getSofZmanTfila(getSunriseBaalHatanya(), getSunsetBaalHatanya(), true);
	}

	/**
	 * This method returns the latest time one is allowed eating <em>chametz</em> on <em>Erev Pesach</em> according to the
	 * opinion of the Baal Hatanya. This time is identical to the {@link #getSofZmanTfilaBaalHatanya() <em>Sof zman
	 * tfilah</em> Baal Hatanya}. This time is 4 hours into the day based on the opinion of the Baal Hatanya that the day
	 * is calculated from sunrise to sunset. This returns the time 4 {@link #getShaahZmanisBaalHatanya()} after
	 * {@link #getSunriseBaalHatanya() <em>netz amiti</em> (sunrise)}. If it is not  <em>erev Pesach</em>, a <code>null</code> will
	 * be returned.
	 * @return the <code>Instant</code> one is allowed eating <em>chametz</em> on <em>Erev Pesach</em>. If it is not <em>erev
	 *         Pesach</em> or the  calculation can't be computed such as in the Arctic Circle where there is at least one
	 *         day a year where the sun does not rise, and one where it does not set, a <code>null</code> will be returned.
	 *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanisBaalHatanya()
	 * @see #getSofZmanTfilaBaalHatanya()
	 * @see #getSofZmanAchilasChametz(Instant, Instant, boolean)
	 */
	public Instant getSofZmanAchilasChametzBaalHatanya() {
		return getSofZmanAchilasChametz(getSunriseBaalHatanya(), getSunsetBaalHatanya(), true);
	}

	/**
	 * This method returns the latest time for burning <em>chametz</em> on <em>Erev Pesach</em> according to the opinion of
	 * the Baal Hatanya. This time is 5 hours into the day based on the opinion of the Baal Hatanya that the day is calculated
	 * from sunrise to sunset. This returns the time 5 * {@link #getShaahZmanisBaalHatanya()} after
	 * {@link #getSunriseBaalHatanya() <em>netz amiti</em> (sunrise)}. If it is not  <em>erev Pesach</em>, a <code>null</code> will
	 * be returned.
	 * @return the <code>Instant</code> of the latest time for burning <em>chametz</em> on <em>Erev Pesach</em>.  If it is not
	 *         <em>erev Pesach</em> or the  calculation can't be computed such as in the Arctic Circle where there is at
	 *         least one day a year where the sun does not rise, and one where it does not set, a <code>null</code> will be
	 *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getShaahZmanisBaalHatanya()
	 * @see #getSofZmanBiurChametz(Instant, Instant, boolean)
	 */
	public Instant getSofZmanBiurChametzBaalHatanya() {
		return getSofZmanBiurChametz(getSunriseBaalHatanya(), getSunsetBaalHatanya(), true);
	}

	/**
	 * This method returns the time of <em>mincha gedola</em>. <em>Mincha gedola</em> is the earliest time one can pray
	 * <em>mincha</em>. The <a href="https://en.wikipedia.org/wiki/Maimonides">Rambam</a> is of the opinion that it is
	 * better to delay <em>mincha</em> until {@link #getMinchaKetanaBaalHatanya() <em>mincha ketana</em>} while the
	 * <a href="https://en.wikipedia.org/wiki/Asher_ben_Jehiel">Ra"sh</a>,
	 * <a href="https://en.wikipedia.org/wiki/Jacob_ben_Asher">Tur</a>, <a href=
	 * "https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a> and others are of the opinion that <em>mincha</em> can be prayed
	 * <em>lechatchila</em> starting at <em>mincha gedola</em>. This is calculated as 6.5 {@link #getShaahZmanisBaalHatanya()
	 * sea level solar hours} after {@link #getSunriseBaalHatanya() <em>netz amiti</em> (sunrise)}. This calculation is based
	 * on the opinion of the Baal Hatanya that the day is calculated from sunrise to sunset. This returns the time 6.5
	 * * {@link #getShaahZmanisBaalHatanya()} after {@link #getSunriseBaalHatanya() <em>netz amiti</em> ("real" sunrise)}.
	 * @todo Consider adjusting this to calculate the time as 30 clock or <em>zmaniyos </em> minutes after either {@link
	 *         getSunTransit() astronomical <em>chatzos</em>} or {@link #getChatzosHayomAsHalfDay() <em>chatzos</em> as half a
	 *          day} for {@link AstronomicalCalculator calculators} that support it, based on {@link #isUseAstronomicalChatzos()}.
	 * @see #getMinchaGedola(Instant, Instant)
	 * @see #getShaahZmanisBaalHatanya()
	 * @see #getMinchaKetanaBaalHatanya()
	 * @return the <code>Instant</code> of the time of <em>mincha gedola</em> according to the Baal Hatanya. If the calculation
	 *         can't be computed such as in the Arctic Circle where there is at least one day a year where the sun does not rise,
	 *         and one where it does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 */
	public Instant getMinchaGedolaBaalHatanya() {
		return getMinchaGedola(getSunriseBaalHatanya(), getSunsetBaalHatanya(), true);
	}

	/**
	 * This method returns the time of <em>mincha ketana</em>. This is the preferred earliest time to pray
	 * <em>mincha</em> in the opinion of the <a href="https://en.wikipedia.org/wiki/Maimonides">Rambam</a> and others.
	 * For more information on this see the documentation on {@link #getMinchaGedolaBaalHatanya() <em>mincha gedola</em>}.
	 * This is calculated as 9.5 {@link #getShaahZmanisBaalHatanya()  sea level solar hours} after {@link #getSunriseBaalHatanya()
	 * <em>netz amiti</em> (sunrise)}. This calculation is calculated based on the opinion of the Baal Hatanya that the
	 * day is calculated from sunrise to sunset. This returns the time 9.5 * {@link #getShaahZmanisBaalHatanya()} after {@link
	 * #getSunriseBaalHatanya() <em>netz amiti</em> (sunrise)}.
	 * 
	 * @see #getMinchaKetana(Instant, Instant)
	 * @see #getShaahZmanisBaalHatanya()
	 * @see #getMinchaGedolaBaalHatanya()
	 * @return the <code>Instant</code> of the time of <em>mincha ketana</em>. If the calculation can't be computed such as
	 *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
	 *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 */
	public Instant getMinchaKetanaBaalHatanya() {
		return getMinchaKetana(getSunriseBaalHatanya(), getSunsetBaalHatanya(), true);
	}

	/**
	 * This method returns the time of <em>plag hamincha</em>. This is calculated as 10.75 hours after sunrise. This calculation
	 * is based on the opinion of the Baal Hatanya that the day is calculated from sunrise to sunset. This returns the time
	 * 10.75 * {@link #getShaahZmanisBaalHatanya()} after {@link #getSunriseBaalHatanya() <em>netz amiti</em> (sunrise)}. See
	 * <a href="https://www.chabad.org/library/article_cdo/aid/3209349/jewish/About-Our-Zmanim-Calculations.htm">About Our
	 * <em>Zmanim</em> Calculations @ Chabad.org</a> for more details on this calculation.
	 * 
	 * @see #getPlagHamincha(Instant, Instant)
	 * @return the <code>Instant</code> of the time of <em>plag hamincha</em>. If the calculation can't be computed such as
	 *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
	 *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 */
	public Instant getPlagHaminchaBaalHatanya() {
		return getPlagHamincha(getSunriseBaalHatanya(), getSunsetBaalHatanya(), true);
	}

	/**
	 * A method that returns <em>tzais</em> (nightfall) when the sun is 6° below the western geometric horizon (90°)
	 * after {@link #getSunset() sunset}.  This <em>tzais</em> / nightfall based on the opinion of the  <a href=
	 * "https://en.wikipedia.org/wiki/Shneur_Zalman_of_Liadi">Baal Hatanya</a>. This calculation is based on the position of the
	 * sun about 24 minutes after {@link #getSeaLevelSunset() sunset} in Jerusalem <a href=
	 * "https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/">around the equinox / equilux</a>, which
	 * is 6° below {@link GEOMETRIC_ZENITH geometric zenith}. See <a href=
	 * "https://www.chabad.org/library/article_cdo/aid/3209349/jewish/About-Our-Zmanim-Calculations.htm">About Our <em>Zmanim</em>
	 * Calculations @ Chabad.org</a> that is based on {@link #getSunsetBaalHatanya() <em>shkiah amitis</em> as
	 * 1.583° below the horizon} calculated <a href="https://kosherjava.com/2022/01/12/equinox-vs-equilux-zmanim-calculations/"
	 * >around the equinox / equilux</a> that computes 3.516 minutes after sunset. To this, 18 minutes of 3/4 of a 24-minute mil and
	 * two minutes for <em>bain hashmashos</em> of Rav Yosi is added. This calculation computes the the sun being 5.83° below
	 * the horizon (very close to the slightly later {@link #getTzaisGeonim5Point95Degrees()} that was calculated based on 4 fixed
	 * minutes) and it is rounded up to 6°.
	 * 
	 * @return The <code>Instant</code> of nightfall. If the calculation can't be computed such as northern and southern
	 *         locations even south of the Arctic Circle and north of the Antarctic Circle where the sun may not reach
	 *         low enough below the horizon for this calculation, a <code>null</code> will be returned. See detailed
	 *         explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getTzaisGeonim5Point95Degrees()
	 * @see #getSunsetBaalHatanya()
	 */
	public Instant getTzaisBaalHatanya() {
		return getSunsetOffsetByDegrees(ZENITH_6_DEGREES);
	}

	/**
	 * This method returns <em>chatzos</em> (midday) following the opinion of the Baal Hatanya that the day for Jewish halachic
	 * times start at {@link #getSunriseBaalHatanya() <em>netz amiti</em> (sunrise)} and ends at {@link #getSunsetBaalHatanya()
	 * <em>shkiah amiti</em> (sunset)}.
	 *
	 * @see AstronomicalCalendar#getSunTransit()
	 * @return the <code>Date</code> of chatzos. If the calculation can't be computed such as in the Arctic Circle where
	 *         there is at least one day where the sun does not rise, and one where it does not set, a null will be
	 *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 */
	public Instant getChatzosBaalHatanya() {
		return getSunTransit(getSunriseBaalHatanya(), getSunsetBaalHatanya());
	}

	/**
	 * This method returns <a href="https://en.wikipedia.org/wiki/Moshe_Feinstein">Rav Moshe Feinstein's</a> opinion of the
	 * calculation of <em>sof zman krias shema</em> (latest time to recite <em>Shema</em> in the morning) according to the
	 * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> that the
	 * day is calculated from dawn to nightfall, but calculated using the first half of the day only. The half a day starts
	 * at <em>alos</em> defined as {@link #getAlos18Degrees() 18°} and ends at {@link #getFixedLocalChatzosHayom() fixed local
	 * chatzos}. <em>Sof Zman Shema</em> is 3 <em>shaos zmaniyos</em> (solar hours) after <em>alos</em> or half of this half-day.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
	 *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
	 *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getAlos18Degrees()
	 * @see #getFixedLocalChatzosHayom()
	 * @see #getHalfDayBasedZman(Instant, Instant, double)
	 */
	public Instant getSofZmanShmaMGA18DegreesToFixedLocalChatzos() {
		return getHalfDayBasedZman(getAlos18Degrees(), getFixedLocalChatzosHayom(), 3);
	}
	
	/**
	 * This method returns <a href="https://en.wikipedia.org/wiki/Moshe_Feinstein">Rav Moshe Feinstein's</a> opinion of the
	 * calculation of <em>sof zman krias shema</em> (latest time to recite <em>Shema</em> in the morning) according to the
	 * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> that the day is calculated
	 * from dawn to nightfall, but calculated using the first half of the day only. The half a day starts at <em>alos</em> defined
	 * as {@link #getAlos16Point1Degrees() 16.1°} and ends at {@link #getFixedLocalChatzosHayom() fixed local chatzos}. <em>Sof Zman
	 * Shema</em> is 3 <em>shaos zmaniyos</em> (solar hours) after this <em>alos</em> or half of this half-day.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
	 *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned.
	 *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getAlos16Point1Degrees()
	 * @see #getFixedLocalChatzosHayom()
	 * @see #getHalfDayBasedZman(Instant, Instant, double)
	 */
	public Instant getSofZmanShmaMGA16Point1DegreesToFixedLocalChatzos() {
		return getHalfDayBasedZman(getAlos16Point1Degrees(), getFixedLocalChatzosHayom(), 3);
	}
	
	/**
	 * This method returns <a href="https://en.wikipedia.org/wiki/Moshe_Feinstein">Rav Moshe Feinstein's</a> opinion of the
	 * calculation of <em>sof zman krias shema</em> (latest time to recite <em>Shema</em> in the morning) according to the
	 * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> that the
	 * day is calculated from dawn to nightfall, but calculated using the first half of the day only. The half a day starts
	 * at <em>alos</em> defined as {@link #getAlos90Minutes() 90 minutes before sunrise} and ends at {@link #getFixedLocalChatzosHayom()
	 * fixed local chatzos}. <em>Sof Zman Shema</em> is 3 <em>shaos zmaniyos</em> (solar hours) after this <em>alos</em> or
	 * half of this half-day.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
	 *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
	 *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getAlos90Minutes()
	 * @see #getFixedLocalChatzosHayom()
	 * @see #getHalfDayBasedZman(Instant, Instant, double)
	 */
	public Instant getSofZmanShmaMGA90MinutesToFixedLocalChatzos() {
		return getHalfDayBasedZman(getAlos90Minutes(), getFixedLocalChatzosHayom(), 3);
	}
	
	/**
	 * This method returns <a href="https://en.wikipedia.org/wiki/Moshe_Feinstein">Rav Moshe Feinstein's</a> opinion of the
	 * calculation of <em>sof zman krias shema</em> (latest time to recite <em>Shema</em> in the morning) according to the
	 * opinion of the <a href="https://en.wikipedia.org/wiki/Avraham_Gombiner">Magen Avraham (MGA)</a> that the
	 * day is calculated from dawn to nightfall, but calculated using the first half of the day only. The half a day starts
	 * at <em>alos</em> defined as {@link #getAlos72Minutes() 72 minutes before sunrise} and ends at {@link #getFixedLocalChatzosHayom()
	 * fixed local chatzos}. <em>Sof Zman Shema</em> is 3 <em>shaos zmaniyos</em> (solar hours) after this <em>alos</em> or
	 * half of this half-day.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
	 *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
	 *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getAlos72Minutes()
	 * @see #getFixedLocalChatzosHayom()
	 * @see #getHalfDayBasedZman(Instant, Instant, double)
	 */
	public Instant getSofZmanShmaMGA72MinutesToFixedLocalChatzos() {
		return getHalfDayBasedZman(getAlos72Minutes(), getFixedLocalChatzosHayom(), 3);
	}
		
	/**
	 * This method returns <a href="https://en.wikipedia.org/wiki/Moshe_Feinstein">Rav Moshe Feinstein's</a> opinion of the
	 * calculation of <em>sof zman krias shema</em> (latest time to recite <em>Shema</em> in the morning) according to the opinion
	 * of the <a href="https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a> that the day is calculated from sunrise to sunset, but
	 * calculated using the first half of the day only. The half a day starts at {@link #getSunset() sunrise} and
	 * ends at {@link #getFixedLocalChatzosHayom() fixed local chatzos}. <em>Sof zman Shema</em> is 3 <em>shaos zmaniyos</em> (solar
	 * hours) after sunrise or half of this half-day.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
	 *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
	 *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getSunset()
	 * @see #getFixedLocalChatzosHayom()
	 * @see #getHalfDayBasedZman(Instant, Instant, double)
	 */
	public Instant getSofZmanShmaGRASunriseToFixedLocalChatzos() {
		return getHalfDayBasedZman(getSunriseBasedOnElevationSetting(), getFixedLocalChatzosHayom(), 3);
	}
	
	/**
	 * This method returns <a href="https://en.wikipedia.org/wiki/Moshe_Feinstein">Rav Moshe Feinstein's</a> opinion of the
	 * calculation of <em>sof zman tfila</em> (<em>zman tfilah</em> (the latest time to recite the morning prayers))
	 * according to the opinion of the <a href="https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a> that the day is
	 * calculated from sunrise to sunset, but calculated using the first half of the day only. The half a day starts at
	 * {@link #getSunset() sunrise} and ends at {@link #getFixedLocalChatzosHayom() fixed local chatzos}. <em>Sof zman
	 * tefila</em> is 4 <em>shaos zmaniyos</em> (solar hours) after sunrise or 2/3 of this half-day.
	 * 
	 * @return the <code>Instant</code> of the latest <em>zman krias shema</em>. If the calculation can't be computed such
	 *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
	 *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
	 *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 * @see #getSunset()
	 * @see #getFixedLocalChatzosHayom()
	 * @see #getHalfDayBasedZman(Instant, Instant, double)
	 */
	public Instant getSofZmanTfilaGRASunriseToFixedLocalChatzos() {
		return getHalfDayBasedZman(getSunriseBasedOnElevationSetting(), getFixedLocalChatzosHayom(), 4);
	}
	
	/**
	 * This method returns <a href="https://en.wikipedia.org/wiki/Moshe_Feinstein">Rav Moshe Feinstein's</a> opinion of
	 * the calculation of <em>mincha gedola</em>, the earliest time one can pray <em>mincha</em> according to the<a href=
	 * "https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a> calculated as 30 minutes after {@link #getFixedLocalChatzosHayom() fixed
	 * local chatzos}.
	 * 
	 * @return the <code>Instant</code> of the time of <em>mincha gedola</em>. If the calculation can't be computed such as
	 *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
	 *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 * 
	 * @see #getMinchaGedolaGRA()
	 * @see #getFixedLocalChatzosHayom()
	 * @see #getMinchaKetanaGRAFixedLocalChatzosToSunset
	 */
	public Instant getMinchaGedolaGRAFixedLocalChatzos30Minutes() {
		return getTimeOffset(getFixedLocalChatzosHayom(), MINUTE_MILLIS * 30);
	}
	
	/**
	 * This method returns <a href="https://en.wikipedia.org/wiki/Moshe_Feinstein">Rav Moshe Feinstein's</a> opinion
	 * of the calculation of <em>mincha ketana</em> (the preferred time to recite the <em>mincha prayers</em> according to
	 * the opinion of the <a href="https://en.wikipedia.org/wiki/Maimonides">Rambam</a> and others) calculated according
	 * to the <a href="https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a> that is 3.5 <em>shaos zmaniyos</em> (solar
	 * hours) after {@link #getFixedLocalChatzosHayom() fixed local chatzos}.
	 * 
	 * @return the <code>Instant</code> of the time of <em>mincha gedola</em>. If the calculation can't be computed such as
	 *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
	 *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 *         
	 * @see #getMinchaGedolaGRA()
	 * @see #getFixedLocalChatzosHayom()
	 * @see #getMinchaGedolaGRAFixedLocalChatzos30Minutes
	 * @see #getHalfDayBasedZman(Instant, Instant, double)
	 */
	public Instant getMinchaKetanaGRAFixedLocalChatzosToSunset() {
		return getHalfDayBasedZman(getFixedLocalChatzosHayom(), getSunsetBasedOnElevationSetting(), 3.5);
	}
	
	/**
	 * This method returns <a href="https://en.wikipedia.org/wiki/Moshe_Feinstein">Rav Moshe Feinstein's</a> opinion
	 * of the calculation of <em>plag hamincha</em>. This method returns <em>plag hamincha</em> calculated according to the
	 * <a href="https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a> that the day ends at sunset and is 4.75 <em>shaos
	 * zmaniyos</em> (solar hours) after {@link #getFixedLocalChatzosHayom() fixed local chatzos}.
	 * 
	 * @return the <code>Instant</code> of the time of <em>mincha gedola</em>. If the calculation can't be computed such as
	 *         in the Arctic Circle where there is at least one day a year where the sun does not rise, and one where it
	 *         does not set, a <code>null</code> will be returned. See detailed explanation on top of the
	 *         {@link AstronomicalCalendar} documentation.
	 *         
	 * @see #getPlagHaminchaGRA()
	 * @see #getFixedLocalChatzosHayom()
	 * @see #getMinchaKetanaGRAFixedLocalChatzosToSunset
	 * @see #getMinchaGedolaGRAFixedLocalChatzos30Minutes
	 * @see #getHalfDayBasedZman(Instant, Instant, double)
	 */
	public Instant getPlagHaminchaGRAFixedLocalChatzosToSunset() {
		return getHalfDayBasedZman(getFixedLocalChatzosHayom(), getSunsetBasedOnElevationSetting(), 4.75);
	}
	
	/**
	 * Method to return <em>tzais</em> (dusk) calculated as 50 minutes after {@link #getSunset() sunset} or {@link
	 * #getSeaLevelSunset() sea level sunset} (depending on the {@link #isUseElevation()} setting). This method returns
	 * <em>tzais</em> (nightfall) based on the opinion of Rabbi Moshe Feinstein for the New York area. This time should
	 * not be used for latitudes other than ones similar to the latitude of the NY area.
	 * 
	 * @return the <code>Instant</code> representing the time. If the calculation can't be computed such as in the Arctic
	 *         Circle where there is at least one day a year where the sun does not rise, and one where it does not set,
	 *         a <code>null</code> will be returned. See detailed explanation on top of the {@link AstronomicalCalendar}
	 *         documentation.
	 */
	public Instant getTzais50Minutes() {
		return getTimeOffset(getSunsetBasedOnElevationSetting(), 50 * MINUTE_MILLIS);
	}
	
	/**
	 * A method for calculating <em>samuch lemincha ketana</em>, / near <em>mincha ketana</em> time that is half an hour before
	 * {@link #getMinchaKetanaGRA()} or is 9 * <em>shaos zmaniyos</em> (solar hours) after the start of
	 * the day, calculated according to the <a href="https://en.wikipedia.org/wiki/Vilna_Gaon">GRA</a> using a day starting at
	 * sunrise and ending at sunset. This is the time that eating or other activity can't begin prior to praying <em>mincha</em>.
	 * The calculation used is 9 * {@link #getShaahZmanisGRA()} after {@link #getSunset() sunrise} or {@link
	 * #getSunriseBasedOnElevationSetting() elevation adjusted sunrise} (depending on the {@link #isUseElevation()} setting). See the
	 * <a href="https://hebrewbooks.org/pdfpager.aspx?req=60387&st=&pgnum=294">Mechaber and Mishna Berurah 232</a> and <a href=
	 * "https://hebrewbooks.org/pdfpager.aspx?req=60388&pgnum=34">249:2</a>.
	 * 
	 * @see #getShaahZmanisGRA()
	 * @see #getSamuchLeMinchaKetana(Instant, Instant, boolean)
	 * @see #isUseAstronomicalChatzosForOtherZmanim()
	 * @return the <code>Instant</code> of the time of <em>samuch lemincha ketana</em>. If the calculation can't be computed such
	 *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
	 *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be
	 *         returned. See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 */
	public Instant getSamuchLeMinchaKetanaGRA() {
		return getSamuchLeMinchaKetana(getSunriseBasedOnElevationSetting(), getSunsetBasedOnElevationSetting(), true);
	}
	
	/**
	 * 
	 * A method for calculating <em>samuch lemincha ketana</em>, / near <em>mincha ketana</em> time that is half an hour before
	 * {@link #getMinchaKetanaGRA()} or is 9 * <em>shaos zmaniyos</em> (solar hours) after the start of the day, calculated based
	 * on a day from   and ending  a day starting at {@link #getMinchaGedola16Point1Degrees() <em>alos</em> 16.1°} and ending
	 * at {@link #getTzais72Minutes() <em>tzais</em> 16.1°}. This is the time that eating or other activity can't begin prior to
	 * praying <em>mincha</em>.  The calculation used is 9 * {@link #getShaahZmanis16Point1Degrees()} after {@link
	 * #getAlos16Point1Degrees() <em>alos</em> 16.1°}. See the <a href=
	 * "https://hebrewbooks.org/pdfpager.aspx?req=60387&st=&pgnum=294">Mechaber and Mishna Berurah 232</a> and <a href=
	 * "https://hebrewbooks.org/pdfpager.aspx?req=60388&pgnum=34">249:2</a>.
	 * 
	 * @see #getSamuchLeMinchaKetana(Instant, Instant, boolean)
	 * @see #getShaahZmanis16Point1Degrees()
	 * @return the <code>Instant</code> of the time of <em>samuch lemincha ketana</em>. If the calculation can't be computed such
	 *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
	 *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned.
	 *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 */
	public Instant getSamuchLeMinchaKetana16Point1Degrees() {
		return getSamuchLeMinchaKetana(getAlos16Point1Degrees(), getTzais16Point1Degrees(), true);
	}
	
	/**
	 * A method for calculating <em>samuch lemincha ketana</em>, / near <em>mincha ketana</em> time that is half an hour before
	 * {@link #getMinchaKetanaGRA()} or is 9 * <em>shaos zmaniyos</em> (solar hours) after the start of the day, calculated based
	 * on a day from   and ending  a day starting at {@link #getAlos72Minutes() <em>alos</em> 72 minutes} and ending at {@link
	 * #getTzais72Minutes() <em>tzais</em> 72 minutes}. This is the time that eating or other activity can't begin prior to praying
	 * <em>mincha</em>. The calculation used is 9 * {@link #getShaahZmanis72Minutes()} after {@link #getAlos72Minutes() <em>alos</em>
	 * 72 minutes}. See the <a href="https://hebrewbooks.org/pdfpager.aspx?req=60387&st=&pgnum=294">Mechaber and Mishna Berurah
	 * 232</a> and <a href="https://hebrewbooks.org/pdfpager.aspx?req=60388&pgnum=34">249:2</a>.
	 * 
	 * @see #getSamuchLeMinchaKetana(Instant, Instant, boolean)
	 * @see #getShaahZmanis72Minutes()
	 * @return the <code>Instant</code> of the time of <em>samuch lemincha ketana</em>. If the calculation can't be computed such
	 *         as northern and southern locations even south of the Arctic Circle and north of the Antarctic Circle
	 *         where the sun may not reach low enough below the horizon for this calculation, a <code>null</code> will be returned.
	 *         See detailed explanation on top of the {@link AstronomicalCalendar} documentation.
	 */
	public Instant getSamuchLeMinchaKetana72Minutes() {
		return getSamuchLeMinchaKetana(getAlos72Minutes(), getTzais72Minutes(), true);
	}
	
	/**
	 * {@summary A method that returns {@link #getSunsetBasedOnElevationSetting() sunset} if it occurs, or the time that the sun
	 * is at its westernmost position (azimuth of 270°), if sunset will not occur that day. In Polar regions (the Arctic or Antarctic
	 * circles), there are days of no sunrise or sunset, and there are opinions that during these periods, the day-night boundary is
	 * when the sun is at its westernmost position}. Sunrise in this opinion is when the sun is at {@link
	 * #getSunriseOrEasternmostSolarAzimuth() azimuth 90°, its easternmost position}. This is the opinion of <a href=
	 * "https://en.wikipedia.org/wiki/Joseph_Schwarz_(geographer)">Rabbi Yehosef Schwarz</a> in his <a href=
	 * "https://hebrewbooks.org/pdfpager.aspx?req=31703&pgnum=134">דברי יוסף – דרך מבוא השמש</a> and <a href=
	 * "https://hebrewbooks.org/pdfpager.aspx?req=159&pgnum=83">דברי יוסף – תשובות, שאלה ח׳</a>. This is brought down <em>lehalacha</em>
	 * by The <a href="https://en.wikipedia.org/wiki/Yosef_Hayyim">Ben Ish Chai</a> in the <a href=
	 * "https://hebrewbooks.org/pdfpager.aspx?req=1401&pgnum=461">רב פעלים – חלק ב׳, סוד ישרים ס׳ ד׳</a>. This time is close to six hours
	 * after {@link #getSunTransit() astronomical <em>chatzos hayom</em>}, but depending on the time of year and location in the
	 *  Arctic / Antarctic, it can be up to 46 minutes before or after this time.
	 * 
	 * @return sunset if it occurs, or the time that the sun will reach its westernmost position (azimuth 270°), if sunset will
	 *         not occur that day. If there is no sunset this day, and the azimuth 270° will not occur, a <code>null</code> will
	 *         be returned.
	 * @see #getSunriseOrEasternmostSolarAzimuth()
	 * @see #getTimeAtAzimuth(double)
	 * @see com.kosherjava.zmanim.util.AstronomicalCalculator#getTimeAtAzimuth(LocalDate, GeoLocation, double)
	 */
	public Instant getSunsetOrWesternmostSolarAzimuth() {
		Instant sunset = getSunsetBasedOnElevationSetting();
		if(sunset != null) {
			return sunset;
		}
		return getTimeAtAzimuth(270);
	}
	
	/**
	 * {@summary A method that returns {@link #getSunriseBasedOnElevationSetting() sunrise} if it occurs, or the time that the sun
	 * is at its easternmost position (azimuth of 90°), if sunrise will not occur that day. In Polar regions (the Arctic or Antarctic
	 * circles), there are days of no sunrise or sunset, and there are opinions that during these periods, the day-night boundary is
	 * when the sun is at its westernmost position}. Sunset in this opinion is when the sun is at {@link
	 * #getSunsetOrWesternmostSolarAzimuth() azimuth 270°, its westernmost position}. This is the opinion of <a href=
	 * "https://en.wikipedia.org/wiki/Joseph_Schwarz_(geographer)">Rabbi Yehosef Schwarz</a> in his <a href=
	 * "https://hebrewbooks.org/pdfpager.aspx?req=31703&pgnum=134">דברי יוסף – דרך מבוא השמש</a> and <a href=
	 * "https://hebrewbooks.org/pdfpager.aspx?req=159&pgnum=83">דברי יוסף – תשובות, שאלה ח׳</a>. This is brought down <em>lehalacha</em>
	 * by The <a href="https://en.wikipedia.org/wiki/Yosef_Hayyim">Ben Ish Chai</a> in the <a href=
	 * "https://hebrewbooks.org/pdfpager.aspx?req=1401&pgnum=461">רב פעלים – חלק ב׳, סוד ישרים ס׳ ד׳</a>. This time is close to six hours
	 * before {@link #getSunTransit() astronomical <em>chatzos hayom</em>}, but depending on the time of year and location in the
	 *  Arctic / Antarctic, it can be up to 46 minutes before or after this time.
	 * 
	 * @return sunrise if it occurs, or the time that the sun will reach its easternmost position (azimuth 90°), if sunrise will
	 *         not occur that day. If there is no sunrise this day, and the azimuth 90° will not occur, a <code>null</code> will
	 *         be returned.
	 * @see #getSunsetOrWesternmostSolarAzimuth()
	 * @see #getTimeAtAzimuth(double)
	 * @see com.kosherjava.zmanim.util.AstronomicalCalculator#getTimeAtAzimuth(LocalDate, GeoLocation, double)
	 */
	public Instant getSunriseOrEasternmostSolarAzimuth() {
		Instant sunrise = getSunriseBasedOnElevationSetting();
		if(sunrise != null) {
			return sunrise;
		}
		return getTimeAtAzimuth(90);
	}
	
	/**
	 * @see java.lang.Object#equals(Object)
	 */
	public boolean equals(Object object) {
		if (this == object) {
			return true;
		}
		if (object == null || getClass() != object.getClass()) {
			return false;
		}
		if (!super.equals(object)) {
			return false;
		}
		ComprehensiveZmanimCalendar that = (ComprehensiveZmanimCalendar) object;
		return ateretTorahSunsetOffset == that.ateretTorahSunsetOffset;
	}

	/**
	 * @see java.lang.Object#hashCode()
	 */
	public int hashCode() {
		return 37 * super.hashCode() + Double.hashCode(ateretTorahSunsetOffset);
	}
}