1998
- Wednesday, 28 January 1998 · Mauni Amavasya
- Thursday, 26 February 1998 · Magha Amavasya
- Saturday, 28 March 1998 · Phalguna Amavasya (Shani)
- Sunday, 26 April 1998 · Chaitra Amavasya
- Monday, 25 May 1998 · Vat Savitri Amavasya (Somvati)
- Wednesday, 24 June 1998 · Jyeshtha Amavasya
- Thursday, 23 July 1998 · Hariyali Amavasya
- Saturday, 22 August 1998 · Shravana Amavasya (Shani)
- Sunday, 20 September 1998 · Mahalaya / Sarvapitri Amavasya
- Tuesday, 20 October 1998 · Diwali (Lakshmi Puja) Amavasya (Bhaumvati)
- Thursday, 19 November 1998 · Kartika Amavasya
- Friday, 18 December 1998 · Margashirsha Amavasya
1999
- Sunday, 17 January 1999 · Mauni Amavasya
- Tuesday, 16 February 1999 · Magha Amavasya (Bhaumvati)
- Wednesday, 17 March 1999 · Phalguna Amavasya
- Friday, 16 April 1999 · Chaitra Amavasya
- Saturday, 15 May 1999 · Vat Savitri Amavasya (Shani)
- Sunday, 13 June 1999 · Adhika Jyeshtha Amavasya
- Tuesday, 13 July 1999 · Jyeshtha Amavasya (Bhaumvati)
- Wednesday, 11 August 1999 · Hariyali Amavasya
- Thursday, 9 September 1999 · Shravana Amavasya
- Saturday, 9 October 1999 · Mahalaya / Sarvapitri Amavasya (Shani)
- Monday, 8 November 1999 · Diwali (Lakshmi Puja) Amavasya (Somvati)
- Tuesday, 7 December 1999 · Kartika Amavasya (Bhaumvati)
How the date is fixed
Every new-moon day, taken as the day on which Amavasya is running at sunrise. One that falls on a Monday is called Somvati, on a Tuesday Bhaumvati, and on a Saturday Shani Amavasya. Amavasya ends the dark half, so both month names are given.
About
Amavasya is the tithi in which the Moon's longitude returns to the Sun's, closing the dark half and, in amanta reckoning, the month itself. It is the tithi of the pitris, and tarpana for ancestors is its regular observance; the aparahna (afternoon) is the governing period for shraddha, so the day whose afternoon carries Amavasya is chosen. Several named Amavasyas stand out: Sarva Pitru Amavasya ending Pitru Paksha, Diwali on Ashwina Amavasya, Mauni Amavasya in Pausha, and any Amavasya on a Monday (Somvati) or Saturday (Shani). Solar eclipses can only occur on Amavasya, which is why eclipse rules are tied to it.
How it is observed
Tarpana for ancestors in the afternoon, river bathing on Somvati and Mauni Amavasya, and lamps at dusk.