Panchang in Davinópolis, Maranhão, Brazil Sun 5 Oct 1980

Shiva’s Pradosh puja is done in pradosha, the 3 muhurtas after sunset. Trayodashi began at 16:40 on Sun 5 Oct, before that evening’s pradosha, and ended at 18:54 on Mon 6 Oct, partway into the next. The Nirnayasindhu takes the evening Trayodashi fills: Sun 5 Oct. 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: 312°–324° is the 27th, Krishna Dwadashi. A day takes the tithi in force at its sunrise, 05:52 here. Ekadashi ended at 14:44 Sat, before it. Dwadashi ends at 16:40, when the lead reaches 324°. The lead passed 180° at the full moon of 24 Sep, so the Moon is waning: Krishna paksha.

The night of Sat 4 Oct ran from sunset 18:03 Sat to sunrise 05:52, 11 h 49 m. Cut into 15 muhurtas of 47 m, its 14th is Brahma Muhurta, the one before the last.

Daylight here, 05:52 to 18:03, 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 night here, 18:03 to 05:52 Mon, 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 fixed stars divide the Moon's path into 27 nakshatras of 13°20′, each in 4 padas of 3°20′. Magha spans 120°00′–133°20′; the Moon entered its pada 3 at 126°40′. It leaves at 17:05, for Purva Phalguni.

Add the Sun's and the Moon's places among the stars: 168.7° + 127.7° = 296.4°. The sum, cut into 27 parts of 13°20′, gives the yoga: 293°20′–306°40′ is the 23rd, Shubha. It ends at 00:49 Mon, then Shukla.

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 03:39, when the lead reached 318°; Taitila runs until 16:40.

A Hindu day runs from one sunrise to the next, not midnight to midnight. This one runs 05:52 to 05:52 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: Simha gives Bhadrapada. The Sun enters Kanya on 16 Sep, inside the month. The next new moon, 8 Oct, finds it in Kanya and begins Ashwina.

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 Oct, with the Sun in Kanya, begins Ashwina. Until then this Krishna paksha reads Ashwina here, and Bhadrapada in the amanta count.

A samvat year begins with Chaitra, the month whose new moon finds the Sun in Meena: 16 Mar 1980, 15:55 Sun. Since then the Sun has moved 195.9° round the stars. Vikram Samvat numbers that year 2037; Shaka Samvat numbers it 1902.