alos72Zmanis
Method to return alos (dawn) calculated using 72 minutes zmaniyos or 1/10th of the day before sunrise.
This is based on an 18-minute Mil so the time for 4 Mil is 72 minutes.
This is 1/10th of a day (12 * 60 = 720), by the calculation that a day starts at sea level sunrise and ends at sea level sunset (or sunrise to sunset, depending on the isUseElevation setting).
The actual calculation is seaLevelSunrise - (shaahZmanisGra * 1.2). This calculation is used in the calendars published by the Hisachdus Harabanim D'Artzos Habris Ve'Canada.
Return
the Date 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 null will be returned. See detailed explanation on top of the AstronomicalCalendar documentation.