Sarvapitra Moksha Amavasya, Amavasya Shraddha, Amavas Shraddha, Mahalaya Amavasya, Sarva pitru Amavasya
The shraddha that is performed on the Amavasya thiti of the Krishna Paksha Bhadrapada Masam or the 15th day of the Bhadrapada month in the waning phase of the moon (no moon) is Amavasya Shraddha. According to North Indian Purnimant Calenders, Amavasya Shraddha falls in the month of Ashwin.
Amavasya Shraddha is the last and the most sacred day among the 15 day long Mahalaya Paksha in the month of Bhadrapada. Shraddha for the ancestors who have died on Amavasya thiti, Purnima Thiti and Chaturdashi Thiti is performed on Amavasya Shraddha.
If the thiti on which the ancestor had died is forgotten or not known then Shraddha should be performed on this day. Also if one is not able to perform Shraddha during one of the days as per thiti of the Mahalaya Paksha, then Shraddha should be perfomed on Amavasya Shraddha. As performing Shraddha on Amavasya Shraddha day is irrespective of thiti and performing of the Shraddha for ancestors would help them to get moksha this Amavasya Shraddha is also known as Sarva Pitra Moksha Amavasya or Sarva Pitri Amavasya.
Shraddha should be performed to please the ancestors, who after satisfied with the process of Shraddha would bless us with wealth and prosperity. During the process of Shraddha care is to be taken, so that the lunch happens only at the Aparahna time of the day, which would be aroung 1-2Pm. Pinda Daan and Tarpan are done as per the process of Shraddha. The Pindas are then either immersed in a river or given as food to a Cow.