Panchang in Chahārbāgh, Alborz Province, Iran Sat 3 Jan 1981

Shiva’s Pradosh puja is done in pradosha, the 3 muhurtas after sunset. Trayodashi runs from 08:25 on Sat 3 Jan to 09:46 on Sun 4 Jan, so only Saturday’s pradosha (17:05–19:55) falls within it. No text giving Pradosh Vrat’s time was found; pradosha is Tithika’s convention.

Pradosh Vrat: every date in Chahārbāgh

The Moon gains on the Sun about 12° a day. Each 12° of lead is one tithi: 312°–324° is the 27th, Krishna Dwadashi. A day takes the tithi in force at its sunrise, 07:17 here. Ekadashi ended at 06:35 Fri, before it. Dwadashi ends at 08:25, when the lead reaches 324°. The lead passed 180° at the full moon of 21 Dec, so the Moon is waning: Krishna paksha.

A day takes the tithi in force at its sunrise. Dwadashi began at 06:35 Fri, before sunrise at 07:17 Fri, and ends at 08:25, after the next sunrise at 07:17. Both days read Dwadashi: it is a vriddhi tithi here.

The night of Fri 2 Jan ran from sunset 17:04 Fri to sunrise 07:17, 14 h 13 m. Cut into 15 muhurtas of 56 m, its 14th is Brahma Muhurta, the one before the last.

Daylight here, 07:17 to 17:05, splits into 8 choghadiyas of 1 h 13 m. Their names follow a fixed order that starts from the weekday, and each name is counted good, neutral or bad.

The night here, 17:05 to 07:17 Sun, splits into 8 choghadiyas of 1 h 46 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′. Anuradha spans 213°20′–226°40′; the Moon entered its pada 3 at 220°. It leaves at 15:17, for Jyeshtha.

Add the Sun's and the Moon's places among the stars: 259.1° + 222.6° = 481.7°, one full turn and 121.7°. Past the turn, cut into 27 parts of 13°20′, it gives the yoga: 120°00′–133°20′ is the 10th, Ganda. It ends at 04:14 Sun, then Vriddhi.

A karana is half a tithi: 6° of the Moon's lead, so the first half of Dwadashi is Kaulava and the second Taitila. Kaulava ended at 19:34 Fri, when the lead reached 318°; Taitila runs until 08:25.

A Hindu day runs from one sunrise to the next, not midnight to midnight. This one runs 07:17 to 07:17 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, 6 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 Jan, with the Sun in Dhanu, begins Pausha. Until then this Krishna paksha reads Pausha here, and Margashirsha in the amanta count.

A samvat year begins with Chaitra, the month whose new moon finds the Sun in Meena: 16 Mar 1980, 22:25 Sun. Since then the Sun has moved 286.3° round the stars. Vikram Samvat numbers that year 2037; Shaka Samvat numbers it 1902.