In every month, in Sukl fortnight, Saptmi and Sasti are generally observed as fast days in reverence to Surya (Sun God). On this day generally the month changes. By observing a fast on this day, one is blessed with imperishable benefits. It is said to bless with the cure of the disease of the eyes and leprosy. A bath in Ganges or sacred rivers and worship of Surya with red flowers of Kaner, red power (gulal), lit lamps and in red clothes, is done. In most of the houses of Hindus, there is the tradition of offering water to the sun, after bath.

Surya Sasti fast (Kartik Sukl Sasti), also called Data Chat, is undertaken after a son is born in the family. It is a three day fast.

The auspicious day of Surya is Sunday; on this day one should not take salt. During the sunlit day, towards evening, one should take one meal consisting of one type of corn. Closing the eyelids, one should look at the sun, for the good of the eyes. That is why this fast is undertaken.