Notes: All timings are represented in 24+ hour notation in local time of New Delhi, India with DST adjustment (if applicable).
Hours past midnight are higher than 24:00 and fall on next day. In Panchang day starts and ends with sunrise.
Upakarma means beginning or Arambham and it refers to the ritualistic beginning of learning Veda. Apart from learning Vedas on Upakarma day, Brahmins ritually change their Upanayana thread along with Shrauta rituals. Upakarma which is a Vedic ritual is still practiced by Hindus of Brahmin community.
Those who follow Yajurveda observe the Upakarma on the full moon day during Shravan month i.e. on Shravana Purnima day. Those who follow Rigveda observe the Upakarma on Shravana Nakshatra day in the month of Shravana. Hence the day to observe Upakarma might differ for the followers of Yajurveda and Rigveda.
Upakarma is known as Avani Avittam in Tamil Nadu. For those who do their first Upakarma, it is known as Thalai Avani Avittam. In Andhra Pradesh, Upakarma during Shravana Purnima is known as Jandhyala Purnima.
Brahmins choose the day of Shravana Purnima to begin the study of Vedas as the day coincides with Hayagriva Jayanti. Hayagriva Jayanti is the birth anniversary of Lord Hayagriva who is considered the incarnation of Lord Vishnu. It is believed that Lord Hayagriva restored all Vedas to Brahma.
The main purpose of the Upakarma ritual is to offer prayers and express the gratitude to those Rishis who gave the knowledge of Vedas and revealed Vedic Mantras to the mankind. The next day of Upakarma is known as Gayatri Japam day.
Those who follow Samaveda observe the Upakarma on Hasta Nakshatra day during Bhadrapada month. Samaveda Upakarma day usually falls after fortnight of Yajurveda and Rigveda Upakarma day.