One of the most important of these ceremonial functions is called Urja-vrata. Urja-vrata is observed in the month of Karttika (October-November); especially in Vrndavana, there is a specific program for temple worship of the Lord in His Damodara form. "Damodara" refers to Krsna's being bound with rope by His mother, Yasoda. It is said that just as Lord Damodara is very dear to His devotees, so the month known as Damodara or Karttika is also very dear to them.

From NoD ch. 12