Shiva Pradosham

Pradosham is a bimonthly occasion on the 13th day (Thrayodashi) of Lunar Calendar.
The auspicious 3 hour period, 1.5 hours (one muhurta) before, and after the sunset is one of the optimum time to worship of Shiva.
“Pra” means removes, and “Dosham” means sins that is the time that removes sins.
If the Pradosham falls on a Saturday then it is referred as Shani Pradosham, which is considered even more auspicious for Lord Shiva.