Panchang in Ipameri, Goiás, Brazil Mon 6 May 2013

Shiva’s Pradosh puja is done in pradosha, the 3 muhurtas after sunset. Trayodashi began at 17:42 on Mon 6 May, before that evening’s pradosha, and ended at 18:31 on Tue 7 May, partway into the next. The Nirnayasindhu takes the evening Trayodashi fills: Mon 6 May. No text giving Pradosh Vrat’s time was found; pradosha is Tithika’s convention.

Pradosh Vrat: every date in Ipameri

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, 06:27 here. Ekadashi ended at 17:22 Sun, before it. Dwadashi ends at 17:42, when the lead reaches 324°. The lead passed 180° at the full moon of 25 Apr, so the Moon is waning: Krishna paksha.

The night of Sun 5 May ran from sunset 17:51 Sun to sunrise 06:27, 12 h 36 m. Cut into 15 muhurtas of 50 m, its 14th is Brahma Muhurta, the one before the last.

Daylight here, 06:27 to 17:50, splits into 8 choghadiyas of 1 h 25 m. Their names follow a fixed order that starts from the weekday, and each name is counted good, neutral or bad.

The night here, 17:50 to 06:27 Tue, splits into 8 choghadiyas of 1 h 34 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′. Uttara Bhadrapada spans 333°20′–346°40′; the Moon entered its pada 3 at 340°. It leaves at 18:10, for Revati.

Add the Sun's and the Moon's places among the stars: 22° + 340.4° = 362.4°, one full turn and 2.4°. Past the turn, cut into 27 parts of 13°20′, it gives the yoga: 0°00′–13°20′ is the 1st, Vishkambha. It ends at 01:37 Tue, then Priti.

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 05:29, when the lead reached 318°; Taitila runs until 17:42.

A Hindu day runs from one sunrise to the next, not midnight to midnight. This one runs 06:27 to 06:27 Tue, so the hours after midnight still belong to Somawara.

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 13 Apr, inside the month. The next new moon, 9 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 9 May, with the Sun in Mesha, begins Vaishakha. Until then this Krishna paksha reads Vaishakha here, and Chaitra in the amanta count.

A samvat year begins with Chaitra, the month whose new moon finds the Sun in Meena: 10 Apr 2013, 06:35 Wed. Since then the Sun has moved 25.4° round the stars. Vikram Samvat numbers that year 2070; Shaka Samvat numbers it 1935.