On 18 October at 0518 ZT, morning stars were observed and the vessel's position was determined to be LAT 25°31.0'N, LONG 146°29.2'E. Your vessel is steaming at 19.0 knots on a course of 308°T. A sextant observation of the Sun's lower limb is made at 0915 ZT. The chronometer reads 11h 17m 11s, and the sextant altitude (hs) is 34°51.4'. The index error is 2.0' off the arc, and the chronometer error is 01m 57s fast. Your height of eye on the bridge is 54.0 feet. What is the azimuth (Zn) of this sight using the assumed position?
Official USCG Answer & Rule Citation
Correct Answer: Option A — 125.5°T
Calculate GMT by adjusting the chronometer reading for error. Extract GHA and Declination from the Nautical Almanac. Using the assumed position, determine the LHA. Applying the Sight Reduction Tables (Pub. 229) for the specific latitude and LHA provides the calculated azimuth of 125.5°T, consistent with standard celestial navigation procedures.
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