Panchang in Codcod, Western Visayas, Philippines Fri 5 Dec 1980

Shiva’s worship centres on nishitha, the midnight muhurta. Chaturdashi runs from 19:06 on Fri 5 Dec to 21:01 on Sat 6 Dec, so only Friday night’s nishitha (23:13–00:02 Sat) falls within it. No text giving Masik Shivratri’s time was found; nishitha is Tithika’s convention.

Masik Shivratri: every date in Codcod

The Moon gains on the Sun about 12° a day. Each 12° of lead is one tithi: 324°–336° is the 28th, Krishna Trayodashi. A day takes the tithi in force at its sunrise, 05:51 here. Dwadashi ended at 16:50 Thu, before it. Trayodashi ends at 19:06, when the lead reaches 336°. The lead passed 180° at the full moon of 22 Nov, so the Moon is waning: Krishna paksha.

The night of Thu 4 Dec ran from sunset 17:23 Thu to sunrise 05:51, 12 h 28 m. Cut into 15 muhurtas of 49 m, its 14th is Brahma Muhurta, the one before the last.

Daylight here, 05:51 to 17:24, 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, 17:24 to 05:52 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′. Swati spans 186°40′–200°00′; the Moon entered its pada 4 at 196°40′. It leaves at 07:20, for Vishakha.

Add the Sun's and the Moon's places among the stars: 229.3° + 199.3° = 428.6°, one full turn and 68.6°. Past the turn, cut into 27 parts of 13°20′, it gives the yoga: 66°40′–80°00′ is the 6th, Atiganda. It ends at 02:50 Sat, then Sukarma.

A karana is half a tithi: 6° of the Moon's lead, so the first half of Trayodashi is Garaja and the second Vanija. Garaja runs until 06:00, when the lead reaches 330°; Vanija until 19:06.

A Hindu day runs from one sunrise to the next, not midnight to midnight. This one runs 05:51 to 05:52 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: Tula gives Kartika. The Sun enters Vrishchika on 16 Nov, inside the month. The next new moon, 7 Dec, finds it in Vrishchika and begins Margashirsha.

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 7 Dec, with the Sun in Vrishchika, begins Margashirsha. Until then this Krishna paksha reads Margashirsha here, and Kartika in the amanta count.

A samvat year begins with Chaitra, the month whose new moon finds the Sun in Meena: 17 Mar 1980, 02:55 Mon. Since then the Sun has moved 256.5° round the stars. Vikram Samvat numbers that year 2037; Shaka Samvat numbers it 1902.