Panchang in Pendleton, Oregon, United States Sat 30 Dec 2017

Shiva’s Pradosh puja is done in pradosha, the 3 muhurtas after sunset. Trayodashi runs from 05:25 on Sat 30 Dec to 01:58 on Sun 31 Dec, so only Saturday’s pradosha (16:20–19:23) falls within it. No text giving Pradosh Vrat’s time was found; pradosha is Tithika’s convention.

Pradosh Vrat: every date in Pendleton

The Moon gains on the Sun about 12° a day. Each 12° of lead is one tithi: 144°–156° is the 13th, Shukla Trayodashi. A day takes the tithi in force at its sunrise, 07:35 here. Dwadashi ended at 05:25, before it. Trayodashi ends at 01:58 Sun, when the lead reaches 156°. The lead passed 0° at the new moon of 17 Dec, so the Moon is waxing: Shukla paksha.

A day takes the tithi in force at its sunrise.

New Delhi · IST

Sunrise here, 07:13, came after Ekadashi ended at 21:54 Fri: this day reads Dwadashi.

Pendleton · UTC−8

Sunrise here, 07:35, came after Dwadashi ended at 05:25: this day reads Trayodashi.

The night of Fri 29 Dec ran from sunset 16:19 Fri to sunrise 07:35, 15 h 16 m. Cut into 15 muhurtas of 1 h 1 m, its 14th is Brahma Muhurta, the one before the last.

Daylight here, 07:35 to 16:20, splits into 8 choghadiyas of 1 h 5 m. Their names follow a fixed order that starts from the weekday, and each name is counted good, neutral or bad.

The night here, 16:20 to 07:36 Sun, splits into 8 choghadiyas of 1 h 54 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′. Rohini spans 40°00′–53°20′; the Moon entered its pada 1 at 40°. It leaves at 04:23 Sun, for Mrigashira.

Add the Sun's and the Moon's places among the stars: 255° + 40.3° = 295.3°. The sum, cut into 27 parts of 13°20′, gives the yoga: 293°20′–306°40′ is the 23rd, Shubha. It ends at 00:34 Sun, then Shukla.

A karana is half a tithi: 6° of the Moon's lead, so the first half of Trayodashi is Kaulava and the second Taitila. Kaulava runs until 15:44, when the lead reaches 150°; Taitila until 01:58 Sun.

A Hindu day runs from one sunrise to the next, not midnight to midnight. This one runs 07:35 to 07:36 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: Dhanu gives Pausha. The Sun enters Makara on 14 Jan, inside the month. The next new moon, 16 Jan, finds it in Makara and begins Magha.

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 17 Dec, with the Sun in Dhanu, began Pausha. This Shukla paksha reads Pausha in both counts.

A samvat year begins with Chaitra, the month whose new moon finds the Sun in Meena: 27 Mar 2017, 19:57 Mon. Since then the Sun has moved 271.5° round the stars. Vikram Samvat numbers that year 2074; Shaka Samvat numbers it 1939.