Panchang in Sevan, Gegharkunik, Armenia Sat 18 Dec 1915

Shiva’s Pradosh puja is done in pradosha, the 3 muhurtas after sunset. Trayodashi runs from 08:20 on Sat 18 Dec to 10:41 on Sun 19 Dec, so only Saturday’s pradosha (16:32–19:29) falls within it. No text giving Pradosh Vrat’s time was found; pradosha is Tithika’s convention.

Pradosh Vrat: every date in Sevan

The Moon gains on the Sun about 12° a day. Each 12° of lead is one tithi: 132°–144° is the 12th, Shukla Dwadashi. A day takes the tithi in force at its sunrise, 07:17 here. Ekadashi ended at 06:17 Fri, before it. Dwadashi ends at 08:22, when the lead reaches 144°. The lead passed 0° at the new moon of 6 Dec, so the Moon is waxing: Shukla paksha.

A day takes the tithi in force at its sunrise. Dwadashi began at 06:17 Fri, before sunrise at 07:16 Fri, and ends at 08:22, after the next sunrise at 07:17. Both days read Dwadashi: it is a vriddhi tithi here.

The night of Fri 17 Dec ran from sunset 16:34 Fri to sunrise 07:17, 14 h 43 m. Cut into 15 muhurtas of 58 m, its 14th is Brahma Muhurta, the one before the last.

Daylight here, 07:17 to 16:34, 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, 16:34 to 07:18 Sun, 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′. Bharani spans 13°20′–26°40′; the Moon entered its pada 4 at 23°20′. It leaves at 08:39, for Krittika.

Add the Sun's and the Moon's places among the stars: 242.5° + 26° = 268.5°. The sum, cut into 27 parts of 13°20′, gives the yoga: 266°40′–280°00′ is the 21st, Siddha. It ends at 04:38 Sun, then Sadhya.

A karana is half a tithi: 6° of the Moon's lead, so the first half of Dwadashi is Bava and the second Balava. Bava ended at 19:17 Fri, when the lead reached 138°; Balava runs until 08:22.

A Hindu day runs from one sunrise to the next, not midnight to midnight. This one runs 07:17 to 07:18 Sun, so the hours after midnight still belong to Shaniwara.

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 15 Dec, inside the month. The next new moon, 5 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 6 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: 15 Mar 1915, 22:41 Mon. Since then the Sun has moved 271° round the stars. Vikram Samvat numbers that year 1972; Shaka Samvat numbers it 1837.