Next sankranti

A saṅkrānti is the Sun’s entry into a sign of the zodiac, which it makes twelve times a year. The texts set a puṇyakāla around each one for the bath, the gifts and the śrāddha, and the day that holds it is the day of the bath and gifts. This site counts the sidereal ingress, by the Lahiri ayanamsa. Dharmasindhu pp. 2⁠–⁠3

Twelve, one for each sign, about a month apart. The Dharmasindhu sorts them into four classes: four viṣṇupada, four ṣaḍaśīti, two viṣuva and two ayana saṅkrāntis. Dharmasindhu p. 3

The puṇyakāla is the time for the bath, the gifts and the śrāddha at a saṅkrānti, and its length depends on the sign: 15 ghaṭīs either side of the ingress for Meṣa and Tulā (the Nirṇaya-sindhu gives 10), 16 before it for Vṛṣabha, Siṃha, Vṛścika and Kumbha, 16 after it for Mithuna, Kanyā, Dhanus and Mīna, 30 before it for Karka and 40 after it for Makara. A ghaṭī is 24 minutes, and only the part in daylight counts, by our reading. The texts do not use the term mahā-puṇyakāla. Dharmasindhu pp. 2⁠–⁠3

The two ayanas: Makara, which begins the Sun’s northward course, and Karka, which begins its southward one. The two viṣuvas, Meṣa and Tulā, come next. The Dharmasindhu ranks the four classes, each more meritorious than the one before: viṣṇupada, ṣaḍaśīti, viṣuva and ayana. The śrāddha is obligatory at the two ayanas. Dharmasindhu pp. 2⁠–⁠3; Nirṇaya-sindhu p. 8

The Sun enters a sign at the same moment everywhere, but sunrise, sunset and midnight come at different hours in each city. An ingress in daylight in one city can fall at night in another, and one before midnight in one city can come after it in another, which moves the bath and gifts to another day. Dharmasindhu p. 2