Navigation Problems USCG Question #9 (Set 1)

On 22 July at 0448 ZT, morning stars were observed, and the vessel's position was determined to be LAT 21°43.0'N, LONG 158°39.0'E. Your vessel is steaming at 21.0 knots on a course of 028°T. A sextant observation of the Sun's lower limb is made at 0956 ZT. The chronometer reads 10h 54m 27s, and the sextant altitude is 54°28.2'. The index error is 1.5' off the arc, and the chronometer error is 01m 38s slow. Your height of eye on the bridge is 56 feet. What is the azimuth (Zn) of this sight using the assumed position?

Official USCG Answer & Rule Citation

Correct Answer: Option A — 086.9°T

Celestial sight reduction requires determining Greenwich Hour Angle (GHA) of Aries and applying sidereal hour angle to find the body's geographic position. Solving the navigational triangle yields the computed altitude and true azimuth (Zn) for the assumed position.

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