Celestial Navigation · Moon — Corrections
Compared with sun and star sights, a moon sight requires the additional, relatively large correction for:
- AIndex error only
- BHorizontal parallax (HP), because the moon is close to the Earth✓ Correct
- CDip only
- DEquation of time
Explanation
The moon's nearness makes its horizontal parallax large and variable, so the moon's altitude correction tables include an HP correction (from the daily pages) in addition to the usual main correction. Semidiameter and the chosen limb are also handled in those tables.
Authority: Nautical Almanac, Moon altitude corrections
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