Scientific Methodology & Ephemeris Verification

1. Orbital Computation Engine

All planetary, solar, and lunar positions within SELENEGAUGE are computed using Astronomy Engine (v2.1.19), authored by Don Cross under the MIT License. Planetary motions are calculated from the VSOP87 theory, while lunar coordinates are derived from the ELP2000-82B analytical theory with complete planetary perturbation expansions.

2. Topocentric Altitude & Atmospheric Refraction

Lunar observations from Earth's surface differ significantly from geocentric positions due to lunar parallax (up to ~1 degree). Our instrument computes true topocentric coordinates based on the observer's exact latitude, longitude, and height above sea level. Apparent altitude calculations incorporate standard atmospheric refraction corrections using Bennett's empirical formula with Garfinkel modifications.

3. U.S. Naval Observatory (USNO) Benchmark Verification

Calculated lunar quarter events are systematically benchmarked against published ephemerides from the U.S. Naval Observatory Astronomical Applications Department. Automated unit tests ensure that computed timestamps for New Moon, First Quarter, and Full Moon events match official USNO ephemerides within a tolerance of less than 3 minutes across target years 2026 and 2027.

4. Operational Limits & Practical Disclaimers

Astronomical computations provide ideal geometric line-of-sight coordinates assuming an unobstructed mathematical horizon at sea level. Actual visibility is constrained by local topography, cloud cover, seeing, atmospheric turbidity, and artificial light pollution.