Annual stellar aberration (~20 arcsec) added to all 6 existing _apparent()
functions via classical first-order v/c projection (Ron & Vondrak). Earth
velocity sourced from VSOP87 xyz[3..5] (analytic) or DE numerical
differentiation.
New functions (106 -> 114):
- eq_angular_distance(): Vincenty formula, stable at 0 and 180 deg
- eq_within_cone(): cosine shortcut for fast cone-search predicate
- <-> operator on equatorial type
- 6 DE apparent variants with VSOP87 fallback:
planet/sun/moon_observe_apparent_de(),
planet/moon_equatorial_apparent_de(),
small_body_observe_apparent_de()
Stellar parallax now functional in star_observe_pm() and
star_equatorial_pm() — Green (1985) Eq. 11.3 displacement using
Earth heliocentric position from VSOP87.
All 19 regression suites pass (18 existing + new aberration suite).
Phase 1 — Stars, comets, Keplerian propagation:
- star_observe() / star_observe_safe(): fixed star alt/az via IAU 1976
precession, equatorial-to-horizontal transform
- kepler_propagate(): two-body Keplerian orbit propagation for
elliptic, parabolic, and hyperbolic orbits
- comet_observe(): observe comets/asteroids from orbital elements
- heliocentric type: ecliptic J2000 position (x, y, z in AU)
Phase 2 — VSOP87 planets, ELP82B Moon, Sun:
- planet_heliocentric(): VSOP87 heliocentric ecliptic J2000 positions
for Mercury through Neptune (Bretagnon & Francou, MIT)
- planet_observe(): full observation pipeline for any planet
- sun_observe(): Sun position from negated Earth VSOP87
- moon_observe(): ELP2000-82B lunar position (Chapront-Touzé, MIT)
- Clean-room precession (IAU 2006) and sidereal time (IERS 2010)
- elliptic_to_rectangular utility (Stellarium, MIT)
All Stellarium extractions are MIT-licensed, thread-safe (static
caching removed for PARALLEL SAFE), zero external data files.
All 9 regression tests pass (90ms total).
