Bava

Bava is the first karana. A karana is half a tithi, the time the Moon takes to gain six degrees on the Sun, so there are two karanas to each lunar day and sixty in a month. The scheme uses eleven named karanas: seven that recur in rotation, the chara or movable karanas, and four that appear only once each, the sthira or fixed karanas clustered around the new moon. Bava is the first of the seven movable karanas, and through the month it recurs eight times. As one of the moving karanas it is regarded in the panchanga as generally benefic, suitable for auspicious and stable undertakings. The karana is one of the five limbs (anga) of the panchanga, the daily Hindu almanac, alongside the tithi, nakshatra, yoga, and weekday. These are the calendar tradition's conventions, resting on the six-degree steps of the Moon away from the Sun.

Varahamihira's sixth century Brihat Samhita is among the earliest surviving texts to treat muhurta, the selection of auspicious moments, in systematic detail, and the karanas take their place there alongside the tithi and nakshatra as one of the factors an electional astrologer weighs; the later Muhurta Chintamani of Daivajna Ramachandra, composed around the turn of the seventeenth century, is the more commonly cited classical handbook in contemporary practice for the detailed rules governing which karana suits which activity. Both belong to a long continuous tradition of muhurta literature in which the karana, as the finest-grained of the five daily limbs, is typically the last factor checked once the coarser tithi and weekday have already been judged favourable.

Sources Muhurta ChintamaniRama Daivajna with Brihat SamhitaVarahamihira

The sixty karanas of a lunation are numbered from the moment of the new moon. The first is Kimstughna, fixed; the last three are Shakuni, Chatushpada and Naga, also fixed; and the fifty six between them are the seven movable karanas turning eight times. Bava heads that rotation, so it takes positions 2, 9, 16, 23, 30, 37, 44 and 51.

Translating those into the almanac: a karana at position p occupies the tithi numbered ceiling of p over two, taking its first half when p is odd and its second when p is even. Bava therefore falls in the second half of tithi 1, the first half of 5, the second of 8, the first of 12, the second of 15, the first of 19, the second of 22 and the first of 26.

Two consequences follow that belong to Bava alone. First, it is the only karana of the eleven that appears five times in the bright fortnight and three in the dark; every other movable karana splits four and four. Second, tithi 15 is Purnima, so Bava holds the second half of the full moon day in every lunation, immediately following the moment of opposition.

Its position at the head of the rotation is also why it is the first karana of the waxing month proper, taking over from Kimstughna as soon as the fixed opening half-tithi is spent.

On the clock, a karana averages 11 hours and 49 minutes, but the Moon's elongation rate varies enough that any one of them can run as short as about ten hours or as long as about thirteen and a half.