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Jyotiṣa & Drik Gaṇita Compendium

Vedic Astronomy & Jyotiṣa Compendium

The theoretical, mathematical, and algorithmic foundation of Vedic calendrics (Panchanga Gaṇita). This compendium documents how ancient observational mandates (*Dṛk-tulyatā*) are implemented via modern high-precision celestial mechanics, JPL numerical ephemerides, and rigorous topocentric horizon models.

Siddhānta Śiromaṇi (Golādhyāya)Ch. Yantrādhyāya, v. 1
A · Canonical text

यत्रोदिते गणिते दृश्याभावो दृश्यते तदा। दृश्यसमं विधेयं स्याद् गणितं दृग्गणितैक्यकृत्॥

yatro dite gaṇite dṛśyābhāvo dṛśyate tadā | dṛśyasamaṃ vidheyaṃ syād gaṇitaṃ dṛggaṇitaikyakṛt ||

Translation:Whenever calculated astronomical positions differ from direct observation in the sky, the calculations must be corrected to match observation. The highest mathematics is that which achieves unity between calculation and observation (Dṛk-Gaṇita-Aikya).
Note: Bhaskaracharya II (1150 CE) explicitly codifies that observational reality supersedes dogmatic or static tables. This verse is the foundational charter of modern Drik Ganita.

Chapters in this Compendium

7 chapters

  • Core Ephemeris

    Astronomical Foundations & Drik Gaṇita

    The evolution from Siddhantic mean motions to modern Drik astronomy, the Saha/Lahiri Calendar Reform (1952–1955), and Swiss Ephemeris DE431 integration.

    Chapter 1

  • Electional

    Muhurta Mechanics & High-Stakes Timing

    The 30 diurnal/nocturnal muhurtas, Choghadiya, Rahu Kalam, Dur Muhurtam weekday matrix, and sectoral industrial/medical electional timing.

    Chapter 4

  • Phenomena

    Grahaṇam (Eclipses) & Sūtak Kaal

    Solar and lunar eclipse contact phases, magnitude/obscuration formulations, the Horizon Visibility Mandate (Dṛśya Niyama), and ritual rules.

    Chapter 5

  • Calendrics

    Sacred Calendars & 100-Year Birthdays

    Solar vs Luni-solar calendars, Amanta vs Purnimanta systems, Adhika/Kshaya Masa algorithms, and 100-year Hindu Tithi birthday calculation.

    Chapter 6

  • Verification

    Verification & Drik Parity

    What the engine's test suite checks, the two parity defects resolved against Drik Panchang's published method, and the city-by-city audit that has not been run.

    Chapter 7

Interactive Solilunar Playground

See the continuous angular mathematics in action across the 5 limbs of the Panchanga.

Panchanga limb sandbox

Illustration, not the engine

Move either longitude and watch the three limbs that follow from them. This classifies a single instant; the engine additionally solves for the moment each limb ends, which is the figure an almanac actually publishes.

Tithi — (Moon − Sun) mod 360, ÷ 12°
Saptamī#7
Śukla pakṣa (waxing) · elongation 82.70° · 89% elapsed
Nakṣatra — Moon ÷ 13°20′
Maghā
#10 · pāda 3
Yoga — (Sun + Moon) mod 360, ÷ 13°20′
Harṣaṇa
#14