The Yajur Upakarma is on the Full Moon of the lunar month Shravana, and the Gayatri japam on the day after. When the Full Moon spans two days, the Ahobila Mutt gives it to the later day only if it runs 12 nazhigai or more past that sunrise. Kalaprakasika uses the same length for a different question: whether the Gayatri homa stays on the Upakarma day. For the date itself, the printed almanac of your tradition decides. A book's rule explains a date; it does not overrule the almanac.
☕ Month, Full Moon, and the day after
Kalaprakasika sets the month: Yajur Vedis keep the Upakarma on the Full Moon day “succeeding the New-Moon of the month of Ashada”, with the Sun in Cancer. The Rig Vedis keep theirs on the day of the Shravana star, and no Upakarma is held in an intercalary month (Kalaprakasika (tr. N. P. Subramania Iyer, 1917), ch. IX, pp. 57–60).
For the day, it measures how long the Full Moon runs after sunrise. If it ends 12 ghatikas or more after sunrise, the Upakarma and the Gayatri homa are both done that day. If it ends sooner, “Upakarma alone should be done on that day and Gayathri Homa on the next.” (Kalaprakasika (tr. N. P. Subramania Iyer, 1917), ch. IX, p. 59).
The Mutt's almanac asks a different question with the same 12 nazhigai (Sri Nrisimha Priya, the Ahobila Mutt's almanac): which day owns the Full Moon. It belongs to the last day whose sunrise it stands on if it runs 12 nazhigai or more past that sunrise, otherwise to the day before. The Gayatri japam follows on the Prathamai after it, by the same rule.
In a year when Shravana comes twice, the Mutt's almanac prints the Upakarma in the first, the extra month. Kalaprakasika, which allows no Upakarma in an intercalary month, points to the regular one.
At a glance
- Kalaprakasika: the Upakarma stays on the Full-Moon day; the length decides whether the Gayatri homa joins it.
- The Mutt: the length decides which day owns the Full Moon, so the Upakarma itself can move to the day before.
- One ghatika is one nazhigai, 24 minutes.
- What Nava does: Yajur Veda Upakarma is the Full Moon of the regular (nija) Shravana, the second in a doubled year, on the day that owns it under the 12-nazhigai rule. Gayatri Japam is the Krishna Prathamai after it, by the same rule. The Mutt's first-month day is not given.
Frequently asked questions
Why is the Upakarma sometimes on the day before the almanac's Full Moon day?
Under the Mutt’s rule a Full Moon that ends less than 12 nazhigai after a sunrise belongs to the day before.
Is the Gayatri japam always the next day?
It is on the Prathamai after the Full Moon, by the same ownership rule, so it is nearly always the day after the Upakarma.
Which Shravana in a year with two?
Traditions differ. The Ahobila Mutt prints it in the first; Nava keeps the regular month. Follow your tradition's almanac.
Deep dive: the 12-nazhigai rule on a sample year
Sunrise 06:00. The Full Moon begins Sunday 08:00 and ends Monday 09:00; Prathamai ends Tuesday 08:30.
🧮 Two rules, one Full Moon
- On Monday the Full Moon runs 3 hours past sunrise, 7.5 nazhigai, under 12.
- The Mutt's rule: the Full Moon belongs to Sunday, the day it began. The Upakarma is Sunday, the Gayatri japam Monday.
- Kalaprakasika's rule: the Upakarma is Monday, the Full-Moon day at sunrise, and since the Full Moon ends within 12 ghatikas, the Gayatri homa moves to Tuesday.
🔗 Read first
This page builds on vyapti, which tithi owns the day, which explains the idea of a tithi owning a day.