Proof - every parameter that moves a chart, published

Hard cases only: a birth two minutes before midnight, one inside a spring-forward gap, one before 1970, one in the southern hemisphere, one near the Arctic circle, one on a nakshatra boundary, one where the dasha balance is a sliver, and one on the equator west of Greenwich. Each table is regenerated by the live engine when this page renders - nothing here is transcribed by hand.

Each of these is a place where two engines legitimately disagree. Where a capability is missing, it says so - the sin is silence, not a short list.

01AyanamsaLahiri (Chitrapaksha), mean

Single supported system today, computed as a polynomial in Julian centuries from J2000 rather than read from a table. True-Chitra, KP-Newcomb and Raman are not offered; that is a limitation, not a default we are hiding.

02Node conventionMean Rahu / Ketu

Rahu is the mean lunar ascending node; Ketu is exactly 180° from it. True-node output is not switchable. Charts built on true nodes will disagree with ours by up to roughly 1.5°.

03Time handlingIANA tzdata via the host Intl database, DST-aware

Offsets are resolved for the birth instant, not for today, so historical DST rules apply wherever the host tzdata carries them. There is no Local Mean Time fallback for births before standard time: a pre-standard-time birth is treated as standard offset. An unknown birth time defaults to 12:00 local and the response flags time_assumed: true and states that the lagna is unreliable.

04House systemWhole sign (rasi bhava)

The lagna rasi is the first bhava in full; every graha's house is its rasi counted from the lagna rasi. Placidus, Sripati and KP cusps are not offered.

05Sunrise definitionDisc centre, standard refraction, spherical horizon at sea level

Sunrise and sunset use an altitude of -0.833° (centre of the disc plus mean refraction), no elevation correction and no upper-limb variant. Engines using the upper limb or a terrain horizon will differ by minutes, which moves every panchang window.

06Divisional chart formulasClassical cyclic division; D1, D2, D3, D7, D9, D10, D12

Each varga sign is floor(sidereal longitude x divisor / 30) mod 12 - the plain cyclical derivation. D16 and above are not published because their competing derivations would need naming before they mean anything. We compute what we list and nothing more.

07Dasha year length365.2425 days (Gregorian mean year)

Vimshottari periods are measured in mean Gregorian years from the exact birth instant, with the first mahadasha reduced by the elapsed fraction of the janma nakshatra. Engines using a 360-day savana year or a sidereal solar year will differ by days over a lifetime - this parameter is the usual reason two dasha tables disagree.

08Rounding and boundariesAssigned on unrounded longitude; displayed to the arc-minute

Rasi, nakshatra and pada are assigned from the full-precision longitude before any rounding, so a graha at 29.9999° stays in its own rasi. Degrees are formatted d° mm' ss" for display only.

09Ephemeris source and versionBuilt-in analytic series - not Swiss Ephemeris

Sun from a truncated VSOP-style series, Moon from truncated ELP2000 terms, and Mercury through Saturn from JPL Keplerian elements. Accuracy is arc-minutes, not arc-seconds: a few arc-minutes for the Sun and Moon, up to roughly a tenth of a degree for the outer grahas. That is fine for rasi, nakshatra, pada, dasha and koota output and is not fine for arc-second work. Every API response carries the engine note stating this.

The eight golden cases are fixtures in this codebase, not screenshots. They live in one file with the engine that evaluates them, so the table above regenerates from source on every deploy. A public repository with a one-command runner is the next step; until it is published, the fixture list and the parameters behind it are here in full.

src/lib/proof-cases.ts       # the 8 golden cases + evaluator
src/lib/pinned-parameters.ts # the 9-point disclosure
src/lib/vedic.ts             # ayanamsa, ascendant, tithi, vimshottari
src/lib/vedic-planets.ts     # nine grahas, houses, sunrise, ashta kuta

Want to check a chart of your own against it? Run one in the browser or connect the API to your assistant and ask it directly.