On 15 November your 0913 zone time fix gives you a position of LAT 22°30.0'N, LONG 68°28.0'W. Your vessel is on course 164°T, and your speed is 13.5 knots. Local apparent noon (LAN) occurs at 1118 zone time at which time meridian altitude of the Sun's lower limb is observed. The observed altitude (Ho) for this sight is 49°46.0'. What is the calculated latitude at LAN?
Official USCG Answer & Rule Citation
Correct Answer: Option A — 21°39.3'N
Advance the 0913 fix to the time of LAN (1118) using the vessel's course and speed. Calculate the Sun's declination at LAN. Using the meridian altitude formula (Lat = 90 - Ho + Dec), determine the latitude at transit as 21°39.3'N, consistent with standard celestial navigation and dead reckoning practices.
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