Astrophysics helpers (wcc_etc.astro)

wcc_etc.astro.get_moon_magnitude(phase, phase_type='fraction', distance_km=384400.0, m_full=-12.74)

Return an approximate V-band magnitude of the Moon.

Parameters - phase: illuminated fraction (0..1) if phase_type=’fraction’, or phase angle in degrees (0=full, 180=new) if phase_type=’angle’. - phase_type: ‘fraction’ or ‘angle’ - distance_km: Earth-Moon distance in km (default mean 384400 km). Magnitude scaled by inverse-square relative to this distance. - m_full: reference full-moon magnitude (default -12.74)

Notes - This is a simple empirical approximation: it assumes brightness scales with illuminated fraction and with inverse-square of distance. - For very small illuminated fractions the function clips fraction to avoid -inf magnitudes.

Example usage

print(“Example moon magnitudes:”) print(” new (frac=0.0):”, get_moon_magnitude(0.0)) print(” first (frac=0.5):”, get_moon_magnitude(0.5)) print(” full (frac=1.0):”, get_moon_magnitude(1.0))

Using phase angles: 0=full, 90=quarter, 180=new

for angle in (0, 90, 180):

print(f”angle {angle} deg -> mag = {get_moon_magnitude(angle, phase_type=’angle’):.2f}”)