Avani Avittam is conducted once a year during the Sravana or Avittam nakshatra of the Hindu calendrical month Sravana (Avani), when Brahmins ritually change their upanayana thread accompanied by relevant srauta rituals, making Sraddha offerings to the rishis, whom Hindus believe composed the Vedic hymns.The day, also called Sravana Poornima “Full Moon of Sravana” in other parts of India, usually occurs the day after the Sravana nakshatra, which also marks the Onam festival of Kerala.
On the following day, usually coinciding with the Raksha Bandhan festival in Northern and Central India, the Gayatri Mantra is recited 1008 times. Brahmins belonging to the Samaveda do not perform upakarma rituals or change their thread on this day but rather on bhadrapada tritiya, the third day of the month bhadrapada with Hasta nakshatra. Shukla Yajurvedic Brahmins of North India and Odisha do upakarma the previous day if the full moon spans two days.
