01What Kartik Purnima is
Kartik Purnima is the full moon that closes Kartik, the month the tradition counts as the most sacred of the lunar year, the month of lamps, early bathing and Vishnu worship. It is one of the largest bathing days of the calendar: crowds gather at Prayag, Varanasi, Pushkar, Haridwar and on riverbanks across the north. In Varanasi it is Dev Deepawali, and on the same day Sikhs celebrate Guru Nanak Jayanti, the birth of the first Sikh Guru. The day is also called Tripuri Purnima, and Bhishma Panchak, the five-day vow that begins on Devutthana Ekadashi, ends on it.
02The story told of it
The name Tripuri Purnima comes from the account the tradition tells of Tripurasura, the three asura brothers whose flying cities of gold, silver and iron could be brought down only by a single arrow, loosed at the moment the three stood in one line. The gods turned to Shiva, who, with the earth as his chariot and Mount Meru as his bow, loosed that one arrow on the full moon of Kartik and ended the three cities, taking the name Tripurari. The tradition holds that the gods came down to the Ganga at Varanasi to celebrate with lamps, and Dev Deepawali, the Diwali of the gods, keeps that memory.
03How it is kept
The tradition keeps the day with a bath before sunrise in a river or temple tank, the closing act of a month of Kartik snan for those who kept it, followed by charity of lamps, food, clothes and grain. Lamps are the mark of the day: in Varanasi the ghats are lined with lakhs of diyas at dusk for Dev Deepawali, and many homes float lamps on water or set them by the tulsi and in temples. The Satyanarayana katha is widely read. Gurdwaras hold the Akhand Path and kirtan for Guru Nanak Jayanti, with nagar kirtan processions and langar open to all.
04How the day is chosen
It is kept on the day its tithi is current at sunrise in your city.
05Kartik Purnima in other years