Krishna Dwadashi

Krishna Dwadashi is the twenty-seventh tithi overall, the twelfth day of the waning fortnight, sacred like its bright counterpart to Vishnu and paired with the Ekadashi fast that precedes it, the fast is broken on this Dwadashi at the proper parana hour. In the fivefold grouping it is a Bhadra or wholesome tithi. The waning crescent is now very thin, rising just before the Sun. In the panchanga Dwadashi is read as auspicious within the constraints of the dark fortnight, and it carries the Vaishnava devotional weight of the twelfth tithi. These are the conventions of the calendar and its observances, in which the eleventh and twelfth tithis of each fortnight form a devotional pair of fast and breaking-of-fast.

The waning Dwadashi's pairing with the preceding Ekadashi fast follows the identical parana logic as the bright-fortnight pair, timed to a specific window after sunrise rather than to the tithi's boundary alone, so the dark half of the month reproduces the same fast-and-breaking structure found in the bright half without alteration, one of the clearest instances in the whole panchanga of a devotional practice applied uniformly across both fortnights regardless of the Moon's waxing or waning. Vaishnava almanacs devote particular attention to correctly identifying this tithi each month precisely because an error in the parana timing is held to diminish the spiritual merit of the entire preceding fast.

The panchanga measures a tithi as an angle rather than a duration: one thirtieth of the circle the Moon travels away from the Sun and back again. Krishna Dwadashi occupies the arc from 312 to 324 degrees of that separation. Since lunar motion quickens and slackens across the month, the arc is crossed in as little as about nineteen hours or as much as about twenty six. The panchanga settles the mismatch by naming each civil day for the tithi in force at its sunrise. A tithi shorter than the interval between two sunrises can therefore be skipped entirely, which the tradition calls a kshaya tithi, and one longer than that interval can carry its name over two civil days, an adhika or vriddhi tithi. Both occur in the ordinary course of a year, and both are why an observance can appear on two dates in the same almanac.

Each tithi is halved again, and each half carries a karana, so the first half of Krishna Dwadashi carries Kaulava, the third, and the second Taitila, the fourth. Seven of the eleven karanas repeat, cycling eight times through the month, while four are fixed to particular half tithis at the month's opening and close.

The Moon is waning through this arc, rising later each night and showing about 13 per cent of the disc lit. The phase follows from the elongation and not the other way round, so the tithi and the shape of the disc are two readings of one measurement.