Panchang in Sevan, Gegharkunik, Armenia Thu 17 Apr 1958

Shiva’s worship centres on nishitha, the midnight muhurta. Chaturdashi runs from 02:17 on Thu 17 Apr to 04:53 on Fri 18 Apr, so only Thursday night’s nishitha (00:38 Fri–01:20 Fri) falls within it. No text giving Masik Shivratri’s time was found; nishitha is Tithika’s convention.

Masik Shivratri: every date in Sevan

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, 06:19 here. Trayodashi ended at 02:17, before it. Chaturdashi ends at 04:53 Fri, when the lead reaches 348°. The lead passed 180° at the full moon of 4 Apr, so the Moon is waning: Krishna paksha.

The night of Wed 16 Apr ran from sunset 19:39 Wed to sunrise 06:19, 10 h 40 m. Cut into 15 muhurtas of 42 m, its 14th is Brahma Muhurta, the one before the last.

Daylight here, 06:19 to 19:40, splits into 8 choghadiyas of 1 h 40 m. Their names follow a fixed order that starts from the weekday, and each name is counted good, neutral or bad.

The night here, 19:40 to 06:18 Fri, splits into 8 choghadiyas of 1 h 19 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 Bhadrapada spans 333°20′–346°40′; the Moon entered its pada 3 at 340°. It leaves at 17:36, for Revati.

Add the Sun's and the Moon's places among the stars: 3.3° + 341.1° = 344.4°. The sum, cut into 27 parts of 13°20′, gives the yoga: 333°20′–346°40′ is the 26th, Indra. It ends at 10:33, then Vaidhriti.

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 15:35, when the lead reaches 342°; Shakuni until 04:53 Fri.

A Hindu day runs from one sunrise to the next, not midnight to midnight. This one runs 06:19 to 06:18 Fri, so the hours after midnight still belong to Guruwara.

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 13 Apr, inside the month. The next new moon, 19 Apr, 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 19 Apr, with the Sun in Mesha, begins Vaishakha. Until then this Krishna paksha reads Vaishakha here, and Chaitra in the amanta count.

A samvat year begins with Chaitra, the month whose new moon finds the Sun in Meena: 20 Mar 1958, 13:49 Thu. Since then the Sun has moved 27.3° round the stars. Vikram Samvat numbers that year 2015; Shaka Samvat numbers it 1880.