Panchang in Chahārbāgh, Alborz Province, Iran Sat 15 Jan 2022

Shiva’s Pradosh puja is done in pradosha, the 3 muhurtas after sunset. Trayodashi runs from 20:19 on Fri 14 Jan to 22:57 on Sat 15 Jan, so only Saturday’s pradosha (17:16–20:04) 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: 144°–156° is the 13th, Shukla Trayodashi. A day takes the tithi in force at its sunrise, 07:16 here. Dwadashi ended at 20:19 Fri, before it. Trayodashi ends at 22:57, when the lead reaches 156°. The lead passed 0° at the new moon of 2 Jan, so the Moon is waxing: Shukla paksha.

The night of Fri 14 Jan ran from sunset 17:15 Fri to sunrise 07:16, 14 h 1 m. Cut into 15 muhurtas of 56 m, its 14th is Brahma Muhurta, the one before the last.

Daylight here, 07:16 to 17:16, splits into 8 choghadiyas of 1 h 15 m. Their names follow a fixed order that starts from the weekday, and each name is counted good, neutral or bad.

The night here, 17:16 to 07:15 Sun, splits into 8 choghadiyas of 1 h 44 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′. Mrigashira spans 53°20′–66°40′; the Moon entered its pada 2 at 56°40′. It leaves at 21:21, for Ardra.

Add the Sun's and the Moon's places among the stars: 270.8° + 59.7° = 330.5°. The sum, cut into 27 parts of 13°20′, gives the yoga: 320°00′–333°20′ is the 25th, Brahma. It ends at 12:32, then Indra.

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 runs until 09:40, when the lead reaches 150°; Taitila until 22:57.

A Hindu day runs from one sunrise to the next, not midnight to midnight. This one runs 07:16 to 07:15 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: Dhanu gives Pausha. The Sun enters Makara on 14 Jan, inside the month. The next new moon, 1 Feb, finds it in Makara and begins Magha.

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 2 Jan, with the Sun in Dhanu, began Pausha. This Shukla paksha reads Pausha in both counts.

A samvat year begins with Chaitra, the month whose new moon finds the Sun in Meena: 12 Apr 2021, 07:00 Mon. Since then the Sun has moved 272.5° round the stars. Vikram Samvat numbers that year 2078; Shaka Samvat numbers it 1943.