Panchang in Codcod, Western Visayas, Philippines Sun 25 Apr 2021

Shiva’s Pradosh puja is done in pradosha, the 3 muhurtas after sunset. Trayodashi runs from 21:47 on Sat 24 Apr to 18:43 on Sun 25 Apr, so it touches only Sunday’s pradosha (17:58–20:17). No text giving Pradosh Vrat’s time was found; pradosha is Tithika’s convention.

Pradosh Vrat: every date in Codcod

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, 05:31 here. Dwadashi ended at 21:47 Sat, before it. Trayodashi ends at 18:43, when the lead reaches 156°. The lead passed 0° at the new moon of 12 Apr, so the Moon is waxing: Shukla paksha.

The night of Sat 24 Apr ran from sunset 17:58 Sat to sunrise 05:31, 11 h 33 m. Cut into 15 muhurtas of 46 m, its 14th is Brahma Muhurta, the one before the last.

Daylight here, 05:31 to 17:58, 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 night here, 17:58 to 05:31 Mon, 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 fixed stars divide the Moon's path into 27 nakshatras of 13°20′, each in 4 padas of 3°20′. Uttara Phalguni spans 146°40′–160°00′; the Moon entered its pada 4 at 156°40′. It leaves at 06:53, for Hasta.

Add the Sun's and the Moon's places among the stars: 10.8° + 159.2° = 170°. The sum, cut into 27 parts of 13°20′, gives the yoga: 160°00′–173°20′ is the 13th, Vyaghata. It ends at 10:43, then Harshana.

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 08:19, when the lead reaches 150°; Taitila until 18:43.

A Hindu day runs from one sunrise to the next, not midnight to midnight. This one runs 05:31 to 05:31 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: Meena gives Chaitra. The Sun enters Mesha on 14 Apr, inside the month. The next new moon, 12 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 12 Apr, with the Sun in Meena, began Chaitra. This Shukla paksha reads Chaitra in both counts.

A samvat year begins with Chaitra, the month whose new moon finds the Sun in Meena: 12 Apr 2021, 10:30 Mon. Since then the Sun has moved 12.5° round the stars. Vikram Samvat numbers that year 2078; Shaka Samvat numbers it 1943.