Celestial Navigation · Sextant Corrections — Upper Limb
When the sun's UPPER limb is observed, the main correction (which includes semidiameter) is:
- ALarger because semidiameter is added
- BSmaller than for the lower limb because the semidiameter is subtracted✓ Correct
- CThe same as the lower limb
- DNever applied
Explanation
For a lower-limb sight the semidiameter (~16') is added; for an upper-limb sight it is subtracted. So the upper-limb correction is roughly 32' less than the lower-limb correction. The Almanac provides separate columns for each limb.
Authority: Nautical Almanac, Altitude Correction Tables
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