Esha← Methodology

Verification

How we verified this engine.

Every astrology app claims to be accurate. Almost none show the work. This page names the specific checks Esha's chart engine has been through — what was tested, against what reference, and what the result was. This is about calculation— the astronomy and the classical arithmetic — not a claim about interpretation's real-world validity; see the honest limit below.

Sub-arcsecond astronomy, cross-checked twice

Esha's chart positions are computed from NASA/JPL planetary ephemeris data (DE440s) in the Lahiri sidereal system, Mean Node stated explicitly. Two independent checks:

  • 25,000 charts vs. Swiss Ephemeris, reading the identical JPL kernel — maximum divergence of about one arcsecond, zero hard errors. Report: ADVERSARIAL_ACCURACY_AUDIT_2026-06-24.
  • 100 charts vs. a separate, independent reference implementation — ascendant, all planets, every divisional chart, all vimśottarī daśā periods, and aṣṭakavarga, byte-for-byte compared. Report: ENGINE_CLASSICAL_ACCURACY_AUDIT_2026-06-24.

Classical arithmetic, module by module

A 7-domain-expert review (Foundation/Pañcāṅga, Divisional charts, Daśā timing, Strength/Bala, Yogas, Jaimini/KP, Predictive/Synthesis) read the actual engine code module by module — 94 modules total — and, wherever feasible, verified each computation against both the running engine and an external oracle. Specific results from that audit:

  • All 16 divisional-chart (varga) mappings exact — zero mismatches over 20,000 random test longitudes each.
  • The full aṣṭakavarga bindu tables exact (sarvāṣṭakavarga total = 337, verified place by place).
  • All six ṣaḍbala (six-fold planetary strength) components fall within their classical [0, 60] range.
  • Vimśottarī daśā verified: the full 120-year cycle, Moon-nakṣatra seed, proportional split, running balance.
  • Aṣṭakūṭa (kundli-matching) point maxima confirmed exactly 36, exhaustively across all 27×27 nakṣatra pairs.
  • Varṣaphala (solar-return) accuracy: the Sun returns to its natal longitude within about 0.05 arcseconds.

Clean-room, provably

No copyleft or proprietary astrology library runs at deploy time — the engine is built on Skyfield and the same public JPL ephemeris data professional astronomers use, not a wrapped third-party library. This is checked two ways every time the codebase changes: a static scan of the shipped source for forbidden imports, and a runtime contamination check. Both must pass before any change can ship — it is a standing gate, not a one-time claim.

Every chart is deterministic: the same birth details always produce the same chart, and every accuracy fix is locked behind a regression test, so a later change cannot silently reintroduce a bug that was already found and corrected.

What this does not claim

This page verifies calculation — where the planets were, and what the classical formulas say about that placement. Astrological interpretation itself carries no such validation claim here, and Esha never states or implies that a reading predicts real-world outcomes. See Methodology for how interpretation is sourced and where the honest limits are.

Ask for the specifics

The reports named above are internal engineering artifacts, not public documents — but the specific numbers on this page are drawn from them directly, not summarised from memory. If you're writing about astrology-app accuracy and want to verify a claim on this page, reach out via Helpand we'll point you to the exact evidence.