Pradosh Vrat or Pradosha Shiva Puja is observed on Trayodasi or the 13th day in every fortnight of Hindu month. In May 2011, the first Pradosh vrat date is 15 May 2011, today. It is known as Bhanu Pradosh as it falls on Sunday. Generally, Pradosh puja time is 4.30 to 6 in the evening.
This Pradosh falls in Narasimha Panchak. The period of 5 days from Mohini Ekadasi to Vaisakha Purnima is observed as Narasimha Panchak.