Somvati Amavasya or Ama Somvar vrata is observed on Monday which coincides with Amavasya. 2 May 2011, Monday, is Somvati Amavasya. As Amavasya begins on Monday, it is also considered as Somvati. No Moon starts at 10.24 am on 2 May and ends on 3 May at 12.20 hrs noon.
Somvati Amavas is especially auspicious for Ganga snana and Pitru Tharpan rituals. As it falls in Vaishakh Month, Vaishakh Snan also coincides with Somvati Snana rituals.
It is Vaishakh Amavasya in North Indian Hindi calendars. And Chaitra Amavasya in Marathi, Gujarati, Telugu, and Kannada calendars.