Celestial Navigation · Sextant Corrections — Parallax
Horizontal parallax (HP) is a significant additional correction primarily for the:
- AStars
- BMoon✓ Correct
- CSun only
- DNavigational planets at high altitude
Explanation
Because the moon is so close to Earth, its parallax is large (up to about 1°) and varies with distance, so an HP correction from the daily pages is applied via the moon's altitude-correction tables. Parallax for the sun is small (~0.1') and built into its tables; for stars it is negligible.
Authority: Nautical Almanac, Altitude Correction Tables (Moon)
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