Panchang in Ipameri, Goiás, Brazil Fri 30 Apr 1920

Shiva’s Pradosh puja is done in pradosha, the 3 muhurtas after sunset. Trayodashi runs from 19:27 on Thu 29 Apr to 20:07 on Fri 30 Apr, touching pradosha on both evenings. The Nirnayasindhu takes the evening it holds more of: Fri 30 Apr. 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: 144°–156° is the 13th, Shukla Trayodashi. A day takes the tithi in force at its sunrise, 06:25 here. Dwadashi ended at 19:27 Thu, before it. Trayodashi ends at 20:07, when the lead reaches 156°. The lead passed 0° at the new moon of 18 Apr, so the Moon is waxing: Shukla paksha.

The night of Thu 29 Apr ran from sunset 17:54 Thu to sunrise 06:25, 12 h 31 m. Cut into 15 muhurtas of 50 m, its 14th is Brahma Muhurta, the one before the last.

Daylight here, 06:25 to 17:54, splits into 8 choghadiyas of 1 h 26 m. Their names follow a fixed order that starts from the weekday, and each name is counted good, neutral or bad.

The night here, 17:54 to 06:25 Sat, splits into 8 choghadiyas of 1 h 33 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′. Hasta spans 160°00′–173°20′; the Moon entered its pada 2 at 163°20′. It leaves at 19:44, for Chitra.

Add the Sun's and the Moon's places among the stars: 17° + 166.3° = 183.3°. The sum, cut into 27 parts of 13°20′, gives the yoga: 173°20′–186°40′ is the 14th, Harshana. It ends at 12:20, then Vajra.

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 07:43, when the lead reaches 150°; Taitila until 20:07.

A Hindu day runs from one sunrise to the next, not midnight to midnight. This one runs 06:25 to 06:25 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: Mesha gives Vaishakha. The Sun enters Vrishabha on 13 May, inside the month. The next new moon, 18 May, finds it in Vrishabha and begins Jyeshtha.

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 18 Apr, with the Sun in Mesha, began Vaishakha. This Shukla paksha reads Vaishakha in both counts.

A samvat year begins with Chaitra, the month whose new moon finds the Sun in Meena: 20 Mar 1920, 07:55 Sat. Since then the Sun has moved 40.2° round the stars. Vikram Samvat numbers that year 1977; Shaka Samvat numbers it 1842.