Panchang in Chahārbāgh, Alborz Province, Iran Fri 15 Apr 2011

Shiva’s Pradosh puja is done in pradosha, the 3 muhurtas after sunset. Trayodashi runs from 18:24 on Fri 15 Apr to 14:47 on Sat 16 Apr, so only Friday’s pradosha (19:39–21:50) 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, 06:34 here. Ekadashi ended at 21:40 Thu, before it. Dwadashi ends at 18:24, when the lead reaches 144°. The lead passed 0° at the new moon of 3 Apr, so the Moon is waxing: Shukla paksha.

The night of Thu 14 Apr ran from sunset 19:38 Thu to sunrise 06:34, 10 h 56 m. Cut into 15 muhurtas of 43 m, its 14th is Brahma Muhurta, the one before the last.

Daylight here, 06:34 to 19:39, splits into 8 choghadiyas of 1 h 38 m. Their names follow a fixed order that starts from the weekday, and each name is counted good, neutral or bad.

The night here, 19:39 to 06:33 Sat, splits into 8 choghadiyas of 1 h 21 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′. Purva Phalguni spans 133°20′–146°40′; the Moon entered its pada 2 at 136°40′. It leaves at 20:40, for Uttara Phalguni.

Add the Sun's and the Moon's places among the stars: 0.8° + 137.9° = 138.7°. The sum, cut into 27 parts of 13°20′, gives the yoga: 133°20′–146°40′ is the 11th, Vriddhi. It ends at 18:40, then Dhruva.

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 runs until 08:05, when the lead reaches 138°; Balava until 18:24.

A Hindu day runs from one sunrise to the next, not midnight to midnight. This one runs 06:34 to 06:33 Sat, so the hours after midnight still belong to Shukrawara.

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: Meena gives Chaitra. The Sun enters Mesha on 14 Apr, inside the month. The next new moon, 3 May, finds it in Mesha and begins Vaishakha.

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 3 Apr, with the Sun in Meena, began Chaitra. This Shukla paksha reads Chaitra in both counts.

A samvat year begins with Chaitra, the month whose new moon finds the Sun in Meena: 3 Apr 2011, 19:02 Sun. Since then the Sun has moved 11.3° round the stars. Vikram Samvat numbers that year 2068; Shaka Samvat numbers it 1933.