Panchang in Sevan, Gegharkunik, Armenia Tue 29 May 2018

Purnima follows the tithi at sunrise. Purnima runs from 17:10 on Mon 28 May to 18:19 on Tue 29 May, so it holds sunrise only on Tue 29 May, at 05:33. No text giving Purnima’s time was found; sunrise is Tithika’s convention.

Purnima: every date in Sevan

The Moon gains on the Sun about 12° a day. Each 12° of lead is one tithi: 168°–180° is the 15th, Shukla Purnima. A day takes the tithi in force at its sunrise, 05:33 here. Chaturdashi ended at 17:10 Mon, before it. Purnima ends at 18:19, when the lead reaches 180°. The lead passed 0° at the new moon of 15 May, so the Moon is waxing: Shukla paksha.

The night of Mon 28 May ran from sunset 20:21 Mon to sunrise 05:33, 9 h 12 m. Cut into 15 muhurtas of 36 m, its 14th is Brahma Muhurta, the one before the last.

Daylight here, 05:33 to 20:21, splits into 8 choghadiyas of 1 h 51 m. Their names follow a fixed order that starts from the weekday, and each name is counted good, neutral or bad.

The night here, 20:21 to 05:32 Wed, splits into 8 choghadiyas of 1 h 8 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 23:25, for Jyeshtha.

Add the Sun's and the Moon's places among the stars: 43.5° + 217.5° = 261°. The sum, cut into 27 parts of 13°20′, gives the yoga: 253°20′–266°40′ is the 20th, Shiva. It ends at 15:42, then Siddha.

A karana is half a tithi: 6° of the Moon's lead, so the first half of Purnima is Vishti and the second Bava. Vishti runs until 05:41, when the lead reaches 174°; Bava until 18:19.

A Hindu day runs from one sunrise to the next, not midnight to midnight. This one runs 05:33 to 05:32 Wed, so the hours after midnight still belong to Mangalawara.

A month normally holds one sankranti, the Sun's entry into a new rashi. From 15 May 15:47 Tue to 13 Jun 23:43 Wed the Sun stayed in Vrishabha, entering Mithuna at 15 Jun 10:06 Fri, after the new moon. A month with no sankranti is Adhika Jyeshtha, before Jyeshtha itself.

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 15 May, with the Sun in Vrishabha, began Jyeshtha (Adhik). This Shukla paksha reads Jyeshtha (Adhik) in both counts.

A samvat year begins with Chaitra, the month whose new moon finds the Sun in Meena: 17 Mar 2018, 17:11 Sat. Since then the Sun has moved 70.7° round the stars. Vikram Samvat numbers that year 2075; Shaka Samvat numbers it 1940.