Panchang in Chahārbāgh, Alborz Province, Iran Sat 16 Dec 2017

Shiva’s worship centres on nishitha, the midnight muhurta. Chaturdashi runs from 05:10 on Sat 16 Dec to 07:29 on Sun 17 Dec, so only Saturday night’s nishitha (23:34–00:31 Sun) falls within it. No text giving Masik Shivratri’s time was found; nishitha is Tithika’s convention.

Masik Shivratri: every date in Chahārbāgh

The Moon gains on the Sun about 12° a day. Each 12° of lead is one tithi: 336°–348° is the 29th, Krishna Chaturdashi. A day takes the tithi in force at its sunrise, 07:10 here. Trayodashi ended at 05:10, before it. Chaturdashi ends at 07:29 Sun, when the lead reaches 348°. The lead passed 180° at the full moon of 3 Dec, so the Moon is waning: Krishna paksha.

A day takes the tithi in force at its sunrise. Chaturdashi began at 05:10, before sunrise at 07:10, and ends at 07:29 Sun, after the next sunrise at 07:10 Sun. Both days read Chaturdashi: it is a vriddhi tithi here.

A day takes the tithi in force at its sunrise.

New Delhi · IST

Sunrise here, 07:06, came before Trayodashi ended at 07:10: this day reads Trayodashi.

Chahārbāgh · UTC+3:30

Sunrise here, 07:10, came after Trayodashi ended at 05:10: this day reads Chaturdashi.

The night of Fri 15 Dec ran from sunset 16:54 Fri to sunrise 07:10, 14 h 16 m. Cut into 15 muhurtas of 57 m, its 14th is Brahma Muhurta, the one before the last.

Daylight here, 07:10 to 16:54, splits into 8 choghadiyas of 1 h 13 m. Their names follow a fixed order that starts from the weekday, and each name is counted good, neutral or bad.

The night here, 16:54 to 07:10 Sun, splits into 8 choghadiyas of 1 h 47 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 2 at 216°40′. It leaves at 02:12 Sun, for Jyeshtha.

Add the Sun's and the Moon's places among the stars: 240.3° + 217.2° = 457.5°, one full turn and 97.5°. 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 00:13 Sun, then Shula.

A karana is half a tithi: 6° of the Moon's lead, so the first half of Chaturdashi is Vishti and the second Shakuni. Vishti runs until 18:18, when the lead reaches 342°; Shakuni until 07:29 Sun.

A Hindu day runs from one sunrise to the next, not midnight to midnight. This one runs 07:10 to 07:10 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, 07:27 Tue. Since then the Sun has moved 256.8° round the stars. Vikram Samvat numbers that year 2074; Shaka Samvat numbers it 1939.