Panchang in Sevan, Gegharkunik, Armenia Sun 15 Dec 2013

The Moon gains on the Sun about 12° a day. Each 12° of lead is one tithi: 144°–156° is the 13th, Shukla Trayodashi. A day takes the tithi in force at its sunrise, 08:16 here. Dwadashi ended at 07:58 Sat, before it. Trayodashi ends at 09:29, when the lead reaches 156°. The lead passed 0° at the new moon of 3 Dec, so the Moon is waxing: Shukla paksha.

A day takes the tithi in force at its sunrise. Trayodashi began at 07:58 Sat, before sunrise at 08:15 Sat, and ends at 09:29, after the next sunrise at 08:16. Both days read Trayodashi: it is a vriddhi tithi here.

The night of Sat 14 Dec ran from sunset 17:33 Sat to sunrise 08:16, 14 h 43 m. Cut into 15 muhurtas of 58 m, its 14th is Brahma Muhurta, the one before the last.

Daylight here, 08:16 to 17:34, splits into 8 choghadiyas of 1 h 9 m. Their names follow a fixed order that starts from the weekday, and each name is counted good, neutral or bad.

The night here, 17:34 to 08:16 Mon, splits into 8 choghadiyas of 1 h 50 m. Their names follow a fixed order that starts from the weekday, and each name is counted good, neutral or bad.

The fixed stars divide the Moon's path into 27 nakshatras of 13°20′, each in 4 padas of 3°20′. Krittika spans 26°40′–40°00′; the Moon entered its pada 3 at 33°20′. It leaves at 18:39, for Rohini.

Add the Sun's and the Moon's places among the stars: 239.3° + 34.7° = 274°. The sum, cut into 27 parts of 13°20′, gives the yoga: 266°40′–280°00′ is the 21st, Siddha. It ends at 19:08, then Sadhya.

A karana is half a tithi: 6° of the Moon's lead, so the first half of Trayodashi is Kaulava and the second Taitila. Kaulava ended at 20:41 Sat, when the lead reached 150°; Taitila runs until 09:29.

A Hindu day runs from one sunrise to the next, not midnight to midnight. This one runs 08:16 to 08:16 Mon, so the hours after midnight still belong to Raviwara.

An amanta month runs from new moon to new moon and takes its name from the rashi the Sun is in at the new moon that begins it: Vrishchika gives Margashirsha. The Sun enters Dhanu on 16 Dec, inside the month. The next new moon, 1 Jan, finds it in Dhanu and begins Pausha.

A purnimanta month runs from full moon to full moon, so its waning half comes first. It shares its name with the amanta month that its second half falls in: the new moon of 3 Dec, with the Sun in Vrishchika, began Margashirsha. This Shukla paksha reads Margashirsha in both counts.

A samvat year begins with Chaitra, the month whose new moon finds the Sun in Meena: 10 Apr 2013, 13:35 Wed. Since then the Sun has moved 242.7° round the stars. Vikram Samvat numbers that year 2070; Shaka Samvat numbers it 1935.