Krishna Dwitiya

Krishna Dwitiya is the seventeenth tithi overall, the second lunar day of the waning fortnight. It carries the character of the second tithi, a Bhadra or wholesome day with Brahma as its traditional deity, but set now in the diminishing light of the dark half. The waning gibbous Moon rises later each night and is past full. The panchanga distinguishes the two fortnights in judging auspicious times, and while the bright fortnight is generally preferred for new undertakings, the dark fortnight has its own suitable observances, including rites for the ancestors. These are the conventions of the Hindu luni-solar calendar, in which every tithi is counted twice a month, once in each paksha, and read partly through its number and partly through the fortnight it falls in.

Because Brahma is assigned as presiding deity to the second tithi in both fortnights, the waning Dwitiya inherits the same creator association as its waxing counterpart even while occupying the structurally opposite, diminishing half of the month, which is a clear instance of how the panchanga's deity assignments track the tithi's fixed number rather than its waxing or waning status. Shraddha rites for ancestors, while concentrated most heavily around Amavasya and the Pitru Paksha fortnight, can in principle be performed on the specific tithi corresponding to a deceased relative's date of death each month, so a family's personal ritual calendar of ancestral observance runs in parallel to, and independently of, the fixed public festival calendar built around particular numbered tithis.

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 Dwitiya occupies the arc from 192 to 204 degrees of that separation. The Moon does not move at a fixed rate, and the same twelve degrees may take a little over nineteen hours near perigee or close to twenty six near apogee. A calendar has to name whole days, so the rule is that whichever tithi is current at sunrise gives the day its name. 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 Dwitiya carries Taitila, the fourth, and the second Gara, the fifth. 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 98 per cent of the disc lit, all but full to the eye. 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.