alos19Point8Degrees
Method to return alos (dawn) calculated when the sun is 19.8˚ below the eastern geometric horizon before sunrise. This calculation is based on the same calculation of 90 minutes 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 around the equinox / equilux, which calculates to 19.8 below geometric zenith.
Return
the Date representing alos. 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.