The first day of Lent — 40 days of penitence before Easter.
Astronomically anchored to Easter (the first Sunday after the first full moon following the spring equinox in the Western tradition). The date is the same globally each year, though Eastern Orthodox traditions use a different rule.
Ash Wednesday marks the start of the 40-day Lenten season of fasting, prayer, and repentance leading to Easter. The name comes from the practice of marking foreheads with ashes — typically burned palm fronds from the previous year's Palm Sunday — as a sign of mortality and penitence.
Computed for Sa Dec (Asia/Ho_Chi_Minh) using local sunrise, sunset and astronomical positions.
Daily tithi, nakshatra, sunrise, sunset and upcoming festivals — all computed for Sa Dec.