Amāvāsyā is the new-moon tithi that closes every dark fortnight, the moonless day that many sūtra and household traditions give to the ancestors. Families offer pitṛ tarpaṇa with sesame and water, give in charity, and remember those who have gone before. The day returns every month, and each new moon is a quiet chance to repay the debt owed to the pitṛs. A few new moons carry special names of their own, but the monthly Amāvāsyā is the steady rhythm beneath them. How the day is fixed: The day is the civil day on which the Amāvāsyā tithi is present at local sunrise. Sunrise differs from place to place, so the date can move by a day between cities. Keep in mind: Families of the Bodhāyana sūtra fix the Darśa karma from how Caturdaśī, Amāvāsyā and Pratipad span the ritual time, which can select a different civil day. If you follow Bodhāyana or another Darśa school, confirm against your family pañcāṅga. This year: The 2027 date shown here is worked out from sunrise at the place you chose, so in another city the same day can fall a day earlier or later. Pitṛ tarpaṇa: After a bath, households offer sesame and water to the departed ancestors, following the gotra rule they already use. Bath and fast: Some bathe in a river or the sea, some keep a light fast, and some offer only water and sesame at home. Worth remembering: Āḍi Amāvāsai, Thai Amāvāsai, Mahālaya Amāvāsai and Bodhāyana Amāvāsai each have their own pages. Mahālaya Amāvāsai closes Pitṛ Pakṣa and is not every monthly new moon. No single all-India menu governs every monthly Amāvāsyā. Some houses keep only the tarpaṇa, while others add a fast, a sea bath or a gift of food. Kulācāra and deśācāra decide these details, so follow the elders of your own house and the gotra rule they taught you.
