it seems a joke
The Hebrew Calender is exactly accurate to the Moon's phase.
The middle of the Hebrew month is of the full Moon and the 2 firsts days are a special Holy days it called ROSH KHODES.
so if you merge your software with this calender will be very nice.
take this as a reference http://tzura.co.il/thesite/hebrew_calendar.asp
this month Dec 1st is also the first Hebrew month KISLEV כסליו
David