Vat Savitri Amavasya

The northern form of the Vat Savitri fast, kept on the new moon of Jyeshtha rather than the full moon.

The same observance splits across regions onto two different tithis a fortnight apart: northern and eastern India keep it on Jyeshtha Amavasya, while Maharashtra and the south keep Vat Purnima on Jyeshtha Purnima. The month is named purnimant here, so the day southern calendars call Vaishakha Amavasya is the same day northern ones call Jyeshtha Amavasya — reading it in the wrong system puts the fast a full month out.