plag
This method should be used lechumra only and returns the time of plag hamincha based on sunrise being 120 minutes zmaniyos or 1/6th of the day before sunrise. This is calculated as 10.75 hours after dawn. The formula used is 10.75 * shaahZmanis120MinutesZmanis after dawn. Since the zman based on an extremely early alos and a very late tzais, it should only be used lechumra.
Return
the Date of the time of plag hamincha. 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.