Panchang in Codcod, Western Visayas, Philippines Sat 16 Dec 2017

Shiva’s worship centres on nishitha, the midnight muhurta. Chaturdashi runs from 09:40 on Sat 16 Dec to 11:59 on Sun 17 Dec, so only Saturday night’s nishitha (23:18–00:07 Sun) 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, 05:57 here. Dwadashi ended at 07:38 Fri, before it. Trayodashi ends at 09:40, when the lead reaches 336°. The lead passed 180° at the full moon of 3 Dec, so the Moon is waning: Krishna paksha.

The night of Fri 15 Dec ran from sunset 17:27 Fri to sunrise 05:57, 12 h 30 m. Cut into 15 muhurtas of 50 m, its 14th is Brahma Muhurta, the one before the last.

Daylight here, 05:57 to 17:28, 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, 17:28 to 05:57 Sun, 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′. Anuradha spans 213°20′–226°40′; the Moon entered its pada 1 at 213°20′. It leaves at 06:42 Sun, for Jyeshtha.

Add the Sun's and the Moon's places among the stars: 240° + 214.3° = 454.3°, one full turn and 94.3°. Past the turn, cut into 27 parts of 13°20′, it gives the yoga: 93°20′–106°40′ is the 8th, Dhriti. It ends at 04:43 Sun, then Shula.

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 ended at 20:37 Fri, when the lead reached 330°; Vanija runs until 09:40.

A Hindu day runs from one sunrise to the next, not midnight to midnight. This one runs 05:57 to 05:57 Sun, so the hours after midnight still belong to Shaniwara.

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: Vrishchika gives Margashirsha. The Sun enters Dhanu on 16 Dec, inside the month. The next new moon, 18 Dec, finds it in Dhanu and begins Pausha.

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 Dec, with the Sun in Dhanu, begins Pausha. Until then this Krishna paksha reads Pausha here, and Margashirsha in the amanta count.

A samvat year begins with Chaitra, the month whose new moon finds the Sun in Meena: 28 Mar 2017, 10:57 Tue. Since then the Sun has moved 256.5° round the stars. Vikram Samvat numbers that year 2074; Shaka Samvat numbers it 1939.