Panchang in Chahārbāgh, Alborz Province, Iran Wed 29 Aug 2012

Shiva’s Pradosh puja is done in pradosha, the 3 muhurtas after sunset. Trayodashi runs from 21:47 on Tue 28 Aug to 20:19 on Wed 29 Aug, touching pradosha on both evenings. The Nirnayasindhu takes the evening it holds more of: Wed 29 Aug. 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, 06:36 here. Dwadashi ended at 21:47 Tue, before it. Trayodashi ends at 20:19, when the lead reaches 156°. The lead passed 0° at the new moon of 17 Aug, so the Moon is waxing: Shukla paksha.

The night of Tue 28 Aug ran from sunset 19:39 Tue to sunrise 06:36, 10 h 57 m. Cut into 15 muhurtas of 43 m, its 14th is Brahma Muhurta, the one before the last.

Daylight here, 06:36 to 19:38, splits into 8 choghadiyas of 1 h 37 m. Their names follow a fixed order that starts from the weekday, and each name is counted good, neutral or bad.

The night here, 19:38 to 06:37 Thu, splits into 8 choghadiyas of 1 h 22 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′. Shravana spans 280°00′–293°20′; the Moon entered its pada 1 at 280°. It leaves at 04:32 Thu, for Dhanishtha.

Add the Sun's and the Moon's places among the stars: 132.1° + 280.8° = 412.9°, one full turn and 52.9°. Past the turn, cut into 27 parts of 13°20′, it gives the yoga: 40°00′–53°20′ is the 4th, Saubhagya. It ends at 07:15, then Shobhana.

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 09:01, when the lead reaches 150°; Taitila until 20:19.

A Hindu day runs from one sunrise to the next, not midnight to midnight. This one runs 06:36 to 06:37 Thu, so the hours after midnight still belong to Budhawara.

A month normally holds one sankranti, the Sun's entry into a new rashi. From 17 Aug 20:24 Fri to 16 Sep 06:40 Sun the Sun stayed in Simha, entering Kanya at 16 Sep 16:54 Sun, after the new moon. A month with no sankranti is Adhika Bhadrapada, before Bhadrapada itself.

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 17 Aug, with the Sun in Simha, began Bhadrapada (Adhik). This Shukla paksha reads Bhadrapada (Adhik) in both counts.

A samvat year begins with Chaitra, the month whose new moon finds the Sun in Meena: 22 Mar 2012, 19:07 Thu. Since then the Sun has moved 153.8° round the stars. Vikram Samvat numbers that year 2069; Shaka Samvat numbers it 1934.