Omitted day (ks.ayadina) Since the average length of a synodic month is about
29.5 days, a month in a lunar calendar consists of either 29 days or 30 days. In
the Indian calendar the concept oftithiplays an important role in order to deter-
mine whether a month contains 29 days or 30 days.
In the earlier period, a tithiwas simply defined as one-thirtieth of a lunar
month, but later it was more exactly defined as the period of time in which the
increment of the lunar longitude over the solar longitude becomes 12 degrees.
In both definitions one month consists inevitably of 30 tithis. A month is divided
into two halves (paks.as), a bright half (s ́uklapaks.a) and a dark half (kr.s.n.apaks.a)
each having 15 tithis. Since the sunrise is the beginning of a civil day, the ordinal
number of a civil day in a half month is determined by the tithiwhich is current
at the sunrise. For instance, as in figure 18.4, if the sixth tithi(t6) is current at
a sunrise, the day is called “sixth day” (d6). In this example, however, the next
day (d7) contains two ends oftithi(t7 and t8) and at the sunrise of the follow-
ing day the ninth tithi (t9) is current. Thus the eighth tithidoes not contribute
to the naming of the civil day. The eighth day (d8), therefore, is omitted from this
half month. This omitted day is called ks.ayadina.
Additional day (adhikadina) Quite opposite to the omitted days, sometimes it
happens that a tithicontains two sunrises. In such case the same date is repeated
and the second one is called adhikadina.In the example of figure 18.5 the eighth
day (d8) of this half month is repeated.
Pañca ̄n.ga The traditional Indian calendar is called pañca ̄n.ga, i.e., “that which is
consisting of five elements.” The five elements are va ̄ra (days of week), tithi,
naks.atra,karan.a, and yoga. The karan.ais a time unit of half oftithi, and the
calendar, astrology, and astronomy 387Vrscika-s.k.
210 °Dhanus-s.k.
240 °Makara-s.k.
270 °Kumbha-s.k.
300 °Asvina ́ Karttika Margasira ́ Magha Phalguna· ́Figure 18.3: Ks.ayama ̄sa(ama ̄ nta system).
sunrise sunrise sunrise sunrise sunrise
d6 d7 d9 d10t6 t7 t8 t9 t10Figure 18.4: Ks.ayadina.