Bengali (West Bengal)

The traditional panjika · sidereal months by the Surya Siddhanta

The Bangabda in its traditional form, kept in West Bengal, Tripura and Assam and printed each year in the panjika, the Bengali almanac. A month begins the day after a sankranti — the moment the sun enters a new sidereal sign — so months run 29 to 32 days and Poila Boishakh falls on 14 or 15 April. The sun in question is not the one overhead but the one described in the Surya Siddhanta, a Sanskrit astronomical treatise of the first millennium, whose model now trails the sky by up to sixteen hours; reckoned by modern astronomy, a good third of the months would open a day earlier than the almanacs have them. When a sankranti lands near midnight in Kolkata, minutes decide the date: in September 2026 the state government moved its Vishwakarma Puja holiday from the 17th to the 18th with only days to spare. The dates here follow the published almanacs, checked month by month from 1419 to 1435; further out they follow the rule alone. Bangladesh reformed all this away in 1987, which is why its calendar reads up to three days ahead.

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