What is the 13th day ceremony after death called?

The 13th day ceremony is called Tehrvin (also spelled Terahvin or Terahi). On this day, the Sapindi Karana ritual is performed — the soul of the recently deceased is formally introduced to the ancestors already in Pitru Loka. The chief mourner shaves his head, the family performs a Brahmin feast (Brahmin Bhoj), and charitable giving (Daan) is done in the name of the deceased. The 13th day marks the end of the Sutak (mourning period), and the family returns to normal life after this ceremony.