General Navigation USCG Question #2190 (Set 67)

At about GMT 1436, on 3 December, the lower limb of the Moon is observed with a sextant having an index error of 2.5' on the arc. The height of eye is 32 feet. The sextant altitude (hs) is 3°38.8'. What is the observed altitude?

Official USCG Answer & Rule Citation

Correct Answer: Option B — Ho 4°29.1'

Per Nautical Almanac procedures, apply index error of 2.5' on the arc (subtract), dip correction for 32 ft height of eye (-5.6'), and main altitude corrections including semidiameter and parallax to find Ho of 4°29.1'.

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