Amavas, or Amavasai or Ammavasi

Amavas, or Amavasai or Ammavasi, is the no moon day in traditional Hindu calendar. It is the darkest day in the traditional Hindu month. Fasting is observed on Amavasi by several communities. Some devout Hindus opt for a single meal on Amavasaiday. The day is considered apt for paying homage to dead ancestors. Here are the Amavas dates in 2009.
(Please note that in some regions Amavas might start a day early and overlap into the next day).
Amavasai dates in 2009 based on Indian Standard Time (IST)
January 25, 2009 – Amavas (In North India, it is on January 26)
February 24, 2009 – Amavasai
March 26, 2009 – Ammavasi
April 25, 2009 – Amavasai
May 24, 2009 – Ammavasi
June 22, 2009 – Amavas
July 22, 2009 – Amavasai (In South it begins on July 21 and ends on July 22 - In Tamil culture Aadi Amavasi is on July 21.)
August 20, 2009 – Ammavasi
September 18, 2009 – Amavas
October 18, 2009 – Ammavasi (begins on October 17)
November 16, 2009 – Amavasai
December 16, 2009 – Amavas
From: http://www.hindu-blog.com/2009/01/amavas-dates-in-2009-amavasai-days.html