Start of month of Nisan on the Hebrew calendar. נִיסָן (transliterated Nisan or Nissan) is the 1st month of the Hebrew year, has30 days, and corresponds to March or April on the Gregorian calendar. רֹאשׁ חוֹדֶשׁ, transliterated Rosh Chodesh or Rosh Hodesh, isa minor holiday that occurs at the beginning of every month in the Hebrewcalendar. It is marked by the birth of a new moon
Torah: Numbers 28:1-15
https://hebcal.com/h/rosh-chodesh-nisan-2025?uc=ical-marietta
