Panchak is a period of five days or tithis or Nakshatras during the transition of Sun from Kumbha rashi to Meena Rashi. Panchak in August 2012 begins on 3 August and ends on 7 August. It starts at 8.55 AM on 3rd and ends at 25.04 hrs on 7th. It is Pratipada to Panchami in Krishna Paksha of Adhik Bhadrapad month in North Indian Hindi calendars; and in Shravan month as per Marathi, Gujarati, Kannada & Telugu calendars.
Dhanista, Shatbhisha, Purva Bhadrapada, Uttara Bhadrapada & Revati Nakshatrams are considered as Panchak Nakshatras. During this period, auspicious events like marriage, gruhapravesh, upanayanam, aksharabhyasam, etc. are avoided.