Star Catalog

157 brightest stars from Yale Bright Star Catalog

RA/Dec coordinates: J2000.0 epoch (±0.01°)

Magnitudes: apparent visual magnitude (V-band)

Spectral classes: Morgan-Keenan system

Coordinate Transforms

GMST: Meeus formula (accurate to ±1 second)

Alt/Az: standard spherical astronomy transforms

Julian Date: precise to ±0.0001 day

Constellations

39 IAU-recognized constellations

Line patterns: traditional Western asterisms

Mythology: Greco-Roman tradition

Planet Positions

Simplified Keplerian elements (mean anomaly + equation of center)

Accuracy: ±2° for inner planets, ±5° for outer planets

NOT JPL-level ephemeris (would need SPICE toolkit)

Moon

Position: simplified Brown's lunar theory (±3°)

Phase: accurate to ±1 day

ISS

Source: wheretheiss.at API (real orbital elements)

Alt/Az from user location: ±1° when visible

What's NOT Accurate

Proper motion of stars not included (negligible for naked-eye)

Atmospheric refraction not modeled (shifts objects near horizon by ~0.5°)

Light pollution not location-specific

Planet brightness (magnitude) not computed

Tech

Three.js r128, WebGL, 53KB, 157 stars, 39 constellations