Upakarma also called Avani Avattam or Janivārada Habba is a Vedic ritual practiced by Hindus of the Brahmin caste. This ritual is also practiced by the Kshatriya and Vaishya community, who are dvijas and therefore have the rights to do Sandhyavandanam, the daily ablution ritual.
Upākarma is conducted once a year during the shravana or Dhanishta Nakshtra of the Hindu calendrical month Shravana when Brahmins ritually change their upanayana thread accompanied by relevant Shrautha rituals, making śrāddha offerings to the rishis, whom Hindus believe composed the Vedic hymns. The day, also called Śshravana Poornima in other parts of India, 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 Bhādrapada Tritiya, the third day of the month Bhādrapada with Hastaa nakshatra.
- Rigveda Upakarma: Should be done on the day in Shraavana when Shravanais the star and spans at least from sunrise to mid day. But not in Uttara Ashadha if present during sunrise.
- Samaveda Upakarma: Should be done on hasta nakshatra on bhadrapada shuklapaksha
- Krishna Yajurveda: i.e. Taittiriyas& Maitrayanis should do on shravistha, dhanistha,(avittam in Tamil), on shraavana month, whether it falls on purnima yukta Pratipada (Pratipat)during sunrise (Telugu- paadyami) or prathama.
- Shukla Yajurveda: i.e. Vajasaneyi Kanvas and Madhyandinas do in purnima day if purnima is present up to evening.But if punima and pratipada both are present on next day(para viddha) they should do on previous day when chaturdashi stays in day and then purnima comes after mid day(purva viddha).Under no condition they should do/avoid doing in krishna paksha pratipat or broadly speaking they should finish upakarma before approach of krishna paksha.but they postpone upakarma to the next day if purnima is having Uttara Ashadha nakshatra.
- Atharva Veda: They do on the day when purnima lasts during sunrise.(udaya vyapini tithi)
