Determining the ruling planet of the day.

In the rich tapestry of Tamil culture, the Panchangam (almanac) is not merely a calendar; it is a spiritual and scientific guide that governs the daily lives of millions. Among the various versions available—such as the popular Vakya Panchangam and Thirukkanitha Panchangam —the holds a unique, almost legendary status. Named after the revered saint and siddhar Pambatti Siddhar (also known as Pamban Swamigal), this almanac is highly regarded for its accuracy in predicting celestial events, particularly the movement of Navagrahas (nine planets) and Nakshatras (lunar mansions).

For further reading on how these traditional units are calculated, you can explore the Panchangam entry on Wikipedia auspicious dates

The is a popular Tamil almanac based on the Vakya (classical oral/vocal) system of astronomical calculation. Its name, which means "Snake Almanac," comes from the prominent image of a snake on its cover, representing the lunar node/Moon.