Panchang in Chahārbāgh, Alborz Province, Iran Thu 5 Aug 2021

Shiva’s Pradosh puja is done in pradosha, the 3 muhurtas after sunset. Trayodashi runs from 16:09 on Thu 5 Aug to 17:28 on Fri 6 Aug, so only Thursday’s pradosha (20:07–22:09) 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, 06:17 here. Ekadashi ended at 14:17 Wed, before it. Dwadashi ends at 16:09, when the lead reaches 324°. The lead passed 180° at the full moon of 24 Jul, so the Moon is waning: Krishna paksha.

The night of Wed 4 Aug ran from sunset 20:08 Wed to sunrise 06:17, 10 h 9 m. Cut into 15 muhurtas of 40 m, its 14th is Brahma Muhurta, the one before the last.

Daylight here, 06:17 to 20:07, splits into 8 choghadiyas of 1 h 43 m. Their names follow a fixed order that starts from the weekday, and each name is counted good, neutral or bad.

The night here, 20:07 to 06:18 Fri, splits into 8 choghadiyas of 1 h 16 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′. Ardra spans 66°40′–80°00′; the Moon entered its pada 1 at 66°40′. It leaves at 05:37 Fri, for Punarvasu.

Add the Sun's and the Moon's places among the stars: 108.7° + 68.1° = 176.8°. The sum, cut into 27 parts of 13°20′, gives the yoga: 173°20′–186°40′ is the 14th, Harshana. It ends at 00:12 Fri, then Vajra.

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 03:17, when the lead reached 318°; Taitila runs until 16:09.

A Hindu day runs from one sunrise to the next, not midnight to midnight. This one runs 06:17 to 06:18 Fri, so the hours after midnight still belong to Guruwara.

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: Mithuna gives Ashadha. The Sun enters Karka on 16 Jul, inside the month. The next new moon, 8 Aug, finds it in Karka and begins Shravana.

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 8 Aug, with the Sun in Karka, begins Shravana. Until then this Krishna paksha reads Shravana here, and Ashadha in the amanta count.

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 110.4° round the stars. Vikram Samvat numbers that year 2078; Shaka Samvat numbers it 1943.