On 22 February your 0612 zone time fix gives you a position of LAT 27°16.2'S, LONG 37°41.6'W. Your vessel is on course 298°T, and your speed is 14.2 knots. Local apparent noon (LAN) occurs at 1147 zone time, at which time a meridian altitude of the Sun's lower limb is observed. The observed altitude (Ho) for this sight is 73°33.3'. What is the calculated latitude at LAN?
Official USCG Answer & Rule Citation
Correct Answer: Option B — 26°31.4'S
Advance the 0612 fix to the time of LAN (1147) using the vessel's course and speed. Determine the Sun's declination at LAN. Apply the meridian altitude formula (Lat = 90 - Ho + Dec) to the corrected Ho to find the latitude at transit, 26°31.4'S, following standard celestial navigation and dead reckoning.
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