Panchang in Chahārbāgh, Alborz Province, Iran Thu 16 May 2019

Shiva’s Pradosh puja is done in pradosha, the 3 muhurtas after sunset. Trayodashi runs from 07:15 on Thu 16 May to 05:04 on Fri 17 May, so only Thursday’s pradosha (20:05–22:04) 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: 132°–144° is the 12th, Shukla Dwadashi. A day takes the tithi in force at its sunrise, 06:01 here. Ekadashi ended at 09:35 Wed, before it. Dwadashi ends at 07:15, when the lead reaches 144°. The lead passed 0° at the new moon of 5 May, so the Moon is waxing: Shukla paksha.

A day takes the tithi in force at its sunrise. Trayodashi began at 07:15 and ended at 05:04 Fri, between the sunrises of 06:01 and 06:00 Fri. Thursday reads Dwadashi and Friday reads Chaturdashi: Trayodashi is a kshaya tithi here.

The night of Wed 15 May ran from sunset 20:04 Wed to sunrise 06:01, 9 h 57 m. Cut into 15 muhurtas of 39 m, its 14th is Brahma Muhurta, the one before the last.

Daylight here, 06:01 to 20:05, splits into 8 choghadiyas of 1 h 45 m. Their names follow a fixed order that starts from the weekday, and each name is counted good, neutral or bad.

The night here, 20:05 to 06:00 Fri, splits into 8 choghadiyas of 1 h 14 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′. Chitra spans 173°20′–186°40′; the Moon entered its pada 1 at 173°20′. It leaves at 03:16 Fri, for Swati.

Add the Sun's and the Moon's places among the stars: 30.8° + 174.1° = 204.9°. The sum, cut into 27 parts of 13°20′, gives the yoga: 200°00′–213°20′ is the 16th, Siddhi. It ends at 19:20, then Vyatipata.

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 20:24 Wed, when the lead reached 138°; Balava runs until 07:15.

A Hindu day runs from one sunrise to the next, not midnight to midnight. This one runs 06:01 to 06:00 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: Mesha gives Vaishakha. The Sun enters Vrishabha on 15 May, inside the month. The next new moon, 3 Jun, finds it in Vrishabha and begins Jyeshtha.

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 5 May, with the Sun in Mesha, began Vaishakha. This Shukla paksha reads Vaishakha in both counts.

A samvat year begins with Chaitra, the month whose new moon finds the Sun in Meena: 5 Apr 2019, 13:20 Fri. Since then the Sun has moved 39.6° round the stars. Vikram Samvat numbers that year 2076; Shaka Samvat numbers it 1941.