Panchang in Thazhecode, Kerala Sat 8 Sep 2018

Shiva’s worship centres on nishitha, the midnight muhurta. Chaturdashi runs from 05:58 on Sat 8 Sep to 02:42 on Sun 9 Sep, so only Saturday night’s nishitha (00:00 Sun–00:47 Sun) falls within it. No text giving Masik Shivratri’s time was found; nishitha is Tithika’s convention.

Masik Shivratri: every date in Thazhecode

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, 06:15 here. Trayodashi ended at 05:58, before it. Chaturdashi ends at 02:42 Sun, when the lead reaches 348°. The lead passed 180° at the full moon of 26 Aug, so the Moon is waning: Krishna paksha.

The night of Fri 7 Sep ran from sunset 18:32 Fri to sunrise 06:15, 11 h 43 m. Cut into 15 muhurtas of 46 m, its 14th is Brahma Muhurta, the one before the last.

Daylight here, 06:15 to 18:31, splits into 8 choghadiyas of 1 h 32 m. Their names follow a fixed order that starts from the weekday, and each name is counted good, neutral or bad.

The night here, 18:31 to 06:15 Sun, splits into 8 choghadiyas of 1 h 28 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′. Ashlesha spans 106°40′–120°00′; the Moon entered its pada 4 at 116°40′. It leaves at 10:29, for Magha.

Add the Sun's and the Moon's places among the stars: 141.2° + 117.4° = 258.6°. The sum, cut into 27 parts of 13°20′, gives the yoga: 253°20′–266°40′ is the 20th, Shiva. It ends at 18:28, then Siddha.

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 16:20, when the lead reaches 342°; Shakuni until 02:42 Sun.

A Hindu day runs from one sunrise to the next, not midnight to midnight. This one runs 06:15 to 06:15 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: Karka gives Shravana. The Sun enters Simha on 17 Aug, inside the month. The next new moon, 9 Sep, finds it in Simha and begins Bhadrapada.

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 9 Sep, with the Sun in Simha, begins Bhadrapada. Until then this Krishna paksha reads Bhadrapada here, and Shravana in the amanta count.

A samvat year begins with Chaitra, the month whose new moon finds the Sun in Meena: 17 Mar 2018, 18:41 Sat. Since then the Sun has moved 168.4° round the stars. Vikram Samvat numbers that year 2075; Shaka Samvat numbers it 1940.