Celestial Navigation · Hour Angle — GHA
To find the GHA of the Sun at a given time, you take the tabulated hourly GHA from the Nautical Almanac and:
- AAdd the declination
- BAdd the increment for minutes and seconds (from the Increments and Corrections pages)✓ Correct
- CSubtract the assumed latitude
- DAdd the dip
Explanation
GHA is interpolated by adding the increment for the minutes and seconds of GMT to the whole-hour tabulated GHA. For the Sun no 'v' correction is normally needed; planets and the Moon use v corrections.
Authority: The Nautical Almanac, Increments and Corrections
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