http://hindupad.com/vratas-pujas/dasavatar-vrat-dashavatara-vratam/
Dasavatar Vrat or Dashavatara Puja is an observance dedicated to all the Dasavataras, Ten Supreme incarnations of Lord Vishnu.
In 2013, Dasavatara Vratham date is September 14. Dashavatar Vratha is observed on the tenth day of Shukla Paksha in Bhadrapad month.
On Dashavathar Puja day, all the ten incarnations of Lord Vishnu are worshipped. Bhadrapad Dashami is very fruitful for the worship of Lord Vishnu and his ten incarnations because during the month two avatars or incarnations of Lord Vishnu – Varaha and Vamana – are appeared.
The next day of Dashavtar Vrata is observed as Padma Parivarthana Ekadashi or Vishnu Parivarthana Ekadasi.
During Dashavthar Pooja, ten avatars – Matsya, Kurma, Varaha, Narasimha, Vamana, Parasurama, Sri Rama, Balarama, Sri Krishna, Kalki avatars – are worshipped.
In Bhadrapad month, Varaha Jayanthi and Vamana Jayanti are celebrated.
