Tithi Calendar | December 2085

Key Dates in December 2085

Festivals, Ekadashi vrats, Purnima (full moon), Amavasya (new moon), and other key dates this month.

How Naksham Computes This Calendar

Naksham reads each tithi from your local sunrise.^[2] This is the Suryodaya Tithi (sunrise-anchored tithi) rule. Drik Panchang and the official Rashtriya Panchang both follow it.^[3] We use the NOAA solar position model for sunrise and sunset. Output is accurate within 1 to 2 minutes for India locations. We use Lahiri ayanamsa (sidereal correction) for sky positions. Festival rules use Chandra masa (lunar month).^[1] By default we count it from the previous Amavasya, the Amanta system used across South and West India. Diwali, the Sawan vrats, and a few other observances instead follow the Purnimanta month, the North Indian count from one full moon to the next. The two systems agree through Shukla Paksha (waxing fortnight) and split by a month through Krishna Paksha (waning fortnight), exactly where these fall, so Naksham matches each festival to the month name it is actually published under. Naksham detects Adhika Masa (extra lunar month) on its own. So festivals stay in the right Vedic month.^[4]

Footnotes

1. [1] Surya Siddhanta (8th century CE), Chapter 2: Madhyamadhikara. The classical Sanskrit text on Hindu astronomy. Defines tithi as 12 degrees of Sun-Moon elongation.
2. [2] Brihat Parashara Hora Shastra (BPHS), Chapter 24: Yoga Karaka Adhyaya. Sage Parashara's foundational text. Establishes the sunrise-anchored Vedic day (Suryodaya Tithi).
3. [3] Drik Panchang convention and Rashtriya Panchang (Government of India, 1957). The official Indian National Calendar reformed by the Calendar Reform Committee under Meghnad Saha. Sets the standard for sunrise-anchored tithi computation.
4. [4] Brihat Parashara Hora Shastra (BPHS), Chapter 86: Festival Determination. Defines festival anchoring by Tithi plus Chandra masa. Adhika Masa rules from the same source. Cross-referenced with Wikipedia: Hindu Calendar.