What are the three Tirthas used in Tarpan and how do they differ?

The Hindu tradition prescribes three specific hand positions called Tirthas for offering water during Tarpan, each used for a different category of beings:

1. Deva Tirtha (Fingertips): Used for offering water to Devas (gods). The performer faces East with the sacred thread in normal position (Savya), holding water in the right hand with the tirtha at the fingertips. Water is offered with one anjali per deity.

2. Kaya Tirtha (Base of the little finger): Used for Rishis and Divya Manushya (divine beings). Facing North, the sacred thread is worn like a necklace (Kanthi). Water mixed with barley is offered from the base of the little finger. Rishi mantras include: Om Marichistripyatam, Om Atristripyatam, Om Angirastripyatam, Om Pulastyastripyatam, Om Pulahastripyatam, Om Kratustripyatam, Om Vashisthastripyatam, Om Prachetastripyatam, Om Bhrigustripyatam, Om Naradastripyatam.

3. Pitru Tirtha (Space between thumb and index finger): Used for ancestors (Pitrus) and Yama. Facing South, with the left knee touching the ground and sacred thread on the right shoulder (Apasavya), water mixed with black sesame seeds is offered through the space between the thumb and index finger. Three anjalis each are offered for the father, grandfather, and great-grandfather forms. This is the most important position during Pitrupaksha Tarpan.