Panchang in Chahārbāgh, Alborz Province, Iran Fri 6 Aug 2021

Shiva’s worship centres on nishitha, the midnight muhurta. Chaturdashi runs from 17:28 on Fri 6 Aug to 18:11 on Sat 7 Aug, so only Friday night’s nishitha (00:52 Sat–01:33 Sat) 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: 324°–336° is the 28th, Krishna Trayodashi. A day takes the tithi in force at its sunrise, 06:18 here. Dwadashi ended at 16:09 Thu, before it. Trayodashi ends at 17:28, when the lead reaches 336°. The lead passed 180° at the full moon of 24 Jul, so the Moon is waning: Krishna paksha.

The night of Thu 5 Aug ran from sunset 20:07 Thu to sunrise 06:18, 10 h 11 m. Cut into 15 muhurtas of 40 m, its 14th is Brahma Muhurta, the one before the last.

Daylight here, 06:18 to 20:06, splits into 8 choghadiyas of 1 h 43 m. Their names follow a fixed order that starts from the weekday, and each name is counted good, neutral or bad.

The night here, 20:06 to 06:19 Sat, splits into 8 choghadiyas of 1 h 16 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′. Punarvasu spans 80°00′–93°20′; the Moon entered its pada 1 at 80°. It leaves at 07:15 Sat, for Pushya.

Add the Sun's and the Moon's places among the stars: 109.7° + 80.4° = 190.1°. The sum, cut into 27 parts of 13°20′, gives the yoga: 186°40′–200°00′ is the 15th, Vajra. It ends at 00:08 Sat, then Siddhi.

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 04:53, when the lead reached 330°; Vanija runs until 17:28.

A Hindu day runs from one sunrise to the next, not midnight to midnight. This one runs 06:18 to 06:19 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: Mithuna gives Ashadha. The Sun enters Karka on 16 Jul, inside the month. The next new moon, 8 Aug, finds it in Karka and begins Shravana.

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 8 Aug, with the Sun in Karka, begins Shravana. Until then this Krishna paksha reads Shravana here, and Ashadha in the amanta count.

A samvat year begins with Chaitra, the month whose new moon finds the Sun in Meena: 12 Apr 2021, 07:00 Mon. Since then the Sun has moved 111.4° round the stars. Vikram Samvat numbers that year 2078; Shaka Samvat numbers it 1943.