Kalashtami or Kala Ashtami is a Hindu festival dedicated to Lord Bhairav and is observed every Hindu lunar month on the ‘Krishna Paksha Ashtami Tithi’ (8th day during the waning phase of moon).
The ‘Ashtami Tithi’ (8th day) after ‘Purnima’ (full moon) is considered to be most suitable day to propitiate Lord Kaal Bhairav. On this day, Hindu devotees worship Lord Bhairav and keep a fast to please Him. There are a total of 12 Kalashtami observances in a year.
Of these, the one falling in the ‘Margashirsha’ month is most significant and is known as ‘Kalabhairav Jayanti’. Kalashtami is also considered holier when it falls on a Sunday or Tuesday, as these days are dedicated to Lord Bhairav.
The most significant Kalashtami, which is known as Kalabhairav Jayanti, falls in the month of Margashirsha according to North Indian, Purnima to Purnima, lunar month calendar while Kalabhairav Jayanti falls in the month of Kartik in South Indian, Amavasya to Amavasya, lunar month calendar. However both calendars observe Kalabhairav Jayanti on the same day. It is believed that Lord Shiva was appeared in form of Bhairav on the same day.