Pradosha vrata
Pradosha vrata is a Hindu vrata for the worship of Lord Shiva and Parvati. The Pradosha worship is done in the evening twilight or sandhya kala on the Trayodashi of both lunar fortnights (Shukla and Krishna Paksha). These are the 13th tithi, or lunar days, from the New Moon (Amavasya) and Full Moon (Poornima).[1][2]
Types of Pradosh Vratas
Of all the pradosha’s Shani Pradosh and Soma Pradosh are considered to be important. Sani Pradosham is the Pradosha Vrata falling on Saturday. And Soma Pradosh is observed when Pradosha falls on a Monday.
Maha Pradhosh is the Pradosha which falls before or on Maha Sivarathri in the month of Maagha in traditional Hindu Calendar.
The performance of the vrata involves a fast followed by a vigil. A bath is taken one hour before sunset and Lord Shiva, Goddess Parvati, Ganesha, Skanda, and Nandi are worshipped. Following this, Lord Shiva is invoked. The Pradosh story is read out after the formal worship is concluded.[1][2]