On 9 November at 0426 ZT, your position was LAT 25°17.0'S, LONG 154°16.0'E. Your vessel is steaming at 14.0 knots on course 066°T. A sextant observation of the Sun's lower limb is made at 0837 ZT. The chronometer reads 10h 35m 21s, and the sextant altitude (hs) is 50°26.9'. The index error is 1.5' on the arc, and the chronometer error is 01m 48s slow. Your height of eye on the bridge is 56.0 feet. What is the observed altitude (Ho) and azimuth (Zn) of this sight using the assumed position?
Official USCG Answer & Rule Citation
Correct Answer: Option D — 50°33.5', 085.9°T
Apply index error and dip correction to the sextant altitude, then use the Nautical Almanac for refraction and parallax. The Sun's GHA and declination are interpolated for the exact GMT. Solving the navigational triangle using the assumed position yields an Ho of 50°33.5' and an azimuth of 085.9°T.
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