Panchang in Davinópolis, Maranhão, Brazil Sun 17 Jul 2016

Shiva’s Pradosh puja is done in pradosha, the 3 muhurtas after sunset. Trayodashi runs from 19:02 on Sat 16 Jul to 19:53 on Sun 17 Jul, touching pradosha on both evenings. The Nirnayasindhu takes the evening it holds more of: Sun 17 Jul. No text giving Pradosh Vrat’s time was found; pradosha is Tithika’s convention.

Pradosh Vrat: every date in Davinópolis

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, 06:20 here. Dwadashi ended at 19:02 Sat, before it. Trayodashi ends at 19:53, when the lead reaches 156°. The lead passed 0° at the new moon of 4 Jul, so the Moon is waxing: Shukla paksha.

The night of Sat 16 Jul ran from sunset 18:10 Sat to sunrise 06:20, 12 h 10 m. Cut into 15 muhurtas of 48 m, its 14th is Brahma Muhurta, the one before the last.

Daylight here, 06:20 to 18:10, splits into 8 choghadiyas of 1 h 28 m. Their names follow a fixed order that starts from the weekday, and each name is counted good, neutral or bad.

The night here, 18:10 to 06:20 Mon, splits into 8 choghadiyas of 1 h 31 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′. Mula spans 240°00′–253°20′; the Moon entered its pada 1 at 240°. It leaves at 06:32 Mon, for Purva Ashadha.

Add the Sun's and the Moon's places among the stars: 91.1° + 240.6° = 331.7°. The sum, cut into 27 parts of 13°20′, gives the yoga: 320°00′–333°20′ is the 25th, Brahma. It ends at 09:14, 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 07:31, when the lead reaches 150°; Taitila until 19:53.

A Hindu day runs from one sunrise to the next, not midnight to midnight. This one runs 06:20 to 06:20 Mon, so the hours after midnight still belong to Raviwara.

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, 2 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 4 Jul, with the Sun in Mithuna, began Ashadha. This Shukla paksha reads Ashadha in both counts.

A samvat year begins with Chaitra, the month whose new moon finds the Sun in Meena: 7 Apr 2016, 08:23 Thu. Since then the Sun has moved 97.1° round the stars. Vikram Samvat numbers that year 2073; Shaka Samvat numbers it 1938.