About the Panchang calendar
What a panchang is
Panchang means five limbs — pancha and anga. It is the Hindu luni-solar almanac, built from the positions of the Sun and the Moon. Its five limbs are tithi, vara, nakshatra, yoga and karana, and between them they date every festival, fast and auspicious window.
The five limbs
Tithi is the lunar day, one for each 12° the Moon pulls ahead of the Sun; thirty make a lunar month. Vara is the weekday. Nakshatra is which of the 27 lunar mansions the Moon stands in. Yoga comes from the Sun and Moon added together, karana is half a tithi. This calendar prints the tithi and nakshatra of each sunrise.
Months and fortnights
Twelve lunar months run Chaitra, Vaishakha, Jyeshtha, Ashadha, Shravana, Bhadrapada, Ashwina, Kartika, Margashirsha, Pausha, Magha, Phalguna. Each splits into two pakshas: Shukla, the waxing half ending at the full moon, and Krishna, the waning half ending at the new moon. Every two or three years an extra month, Adhika Masa, is inserted to keep the lunar year with the solar one.
Vikram Samvat and Shaka Samvat
Two eras are in use. Vikram Samvat runs about 57 years ahead of the Gregorian year; Shaka Samvat runs about 78 behind it, and is India's national calendar. Both are shown in the header, and both turn at Chaitra Shukla Pratipada rather than on 1 January.
Amanta and purnimanta
There are two ways to end a lunar month. The south uses amanta, ending at the new moon; the north uses purnimanta, ending at the full moon. The days are identical either way — only the month a dark-half festival is named for differs, which is why the same festival can carry two month names.