Celestial Navigation · Navigational Triangle — Vertices
The three vertices of the navigational (astronomical) triangle are the:
- AGreenwich, the observer, and the sun
- BElevated pole, the observer's zenith, and the body's position on the celestial sphere✓ Correct
- CNorth pole, south pole, and equator
- DObserver, the GP, and the horizon
Explanation
The spherical navigational triangle is formed by the elevated celestial pole, the observer's zenith, and the celestial body. Its sides are co-latitude, polar distance (co-declination), and co-altitude (zenith distance); the included angles are LHA (or meridian angle t), azimuth angle Z, and the parallactic angle. Sight reduction solves this triangle for Hc and Z.
Authority: Bowditch (Pub. No. 9), The Navigational Triangle
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