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7/4/2026
I built a zero-dependency sky engine in TypeScript, verified to 4.6 arcseconds

I built a zero-dependency sky engine in TypeScript, verified to 4.6 arcseconds

Short summary

A developer released grahan, a zero-dependency TypeScript library computing Sun/Moon positions, sunrise/sunset, and Vedic panchang data, verified to 4.6 arcseconds accuracy. Three engineering decisions drove quality: implementing from academic sources (Meeus, VSOP87) for auditability, pre-committing Swiss Ephemeris reference fixtures to catch bugs early, and CI testing at extreme latitudes that revealed edge cases like polar day reversals. MIT-licensed and production-ready.

  • •Zero-dependency TypeScript library for astronomical calculations and Vedic calendars, verified to 4.6 arcseconds accuracy
  • •Implemented from academic sources (Meeus algorithms, VSOP87 data) for full auditability rather than wrapping external dependencies
  • •Reference fixtures and extreme-latitude CI testing caught subtle bugs: polar-day events, nutation fingerprints, refraction calibration

Generated with AI, which can make mistakes.

#open-source
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