Start of month of Elul on the Hebrew calendar. Elul (אֱלוּל) is the 12th month of the civil Hebrew year (13th on leap years) andthe 6th month of the biblical Hebrew year. It has 29 days and correspondsto August or September on the Gregorian calendar. רֹאשׁ חוֹדֶשׁ, transliterated Rosh Chodesh or Rosh Hodesh, is a minor holiday thatoccurs at the beginning of every month in the Hebrew calendar. It is marked by the birth of a new moon
Torah: Numbers 28:1-15
https://hebcal.com/h/rosh-chodesh-elul-2025?uc=ical-southfield