CRITICAL FIXES FOR SCIENTIFIC ACCURACY (~700 lines):
Time Scale Handling:
- Explicit UTC/TAI/TT/TDB/UT1/GPS conversion
- 37 leap seconds table (current as of 2025)
- UTC→TT: +32.184s after accounting for leap seconds
- UTC→TDB: TT + periodic terms (barycentric time)
- UTC→UT1: Uses IERS EOP data (Earth rotation)
- No more time scale confusion!
Reference Frame Typing:
- ICRF_BARYCENTRIC (JPL ephemerides)
- HELIOCENTRIC_ECLIPTIC (planetary orbits)
- ECI (Earth-Centered Inertial, J2000)
- ECEF (Earth-Centered Earth-Fixed, WGS84)
- TOPOCENTRIC (observer alt/az)
- ECEF↔ECI uses GMST (Greenwich Mean Sidereal Time)
- Frame compatibility validation
Datum Corrections:
- WGS84 Prime Meridian ≠ Greenwich Observatory (~102m offset)
- Ellipsoidal height ≠ Orthometric height (MSL)
- Mount Everest: 8877.69m ellipsoidal vs 8848.86m MSL
- Geoid undulation: -106m to +85m globally
- EGM2008 geoid model support (simplified)
Truth Contract System:
- Every test MUST declare frame + time scale + datum
- Prevents apples-to-oranges comparison
- Typed like a programming language
- Contract validation enforced
Fixes The Two Common Failures:
1. ❌ Time scale mismatch (UTC vs TDB) → ✅ Explicit conversion
2. ❌ Datum confusion (Everest height) → ✅ Ellipsoidal height
This is the difference between 'looks right' and 'IS scientifically correct'
References:
- IERS leap second table (updated 2017-01-01)
- WGS84 corrected landmarks
- GMST formula (IAU 2000)
- Geoid model placeholder (use EGM2008 in production)
