bain
This method returns the beginning of bain hashmashos based on the calculation of 13.5 minutes (3/4 of an 18-minute Mil) before shkiah calculated as 7.083˚.
Return
the Date of the bain hashmashos 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 null will be returned. See detailed explanation on top of the AstronomicalCalendar documentation.