On 13 September your 1830 ZT DR position was LAT 23°03'S, LONG 105°16'E when you observed a faint unidentifiable star through a hole in the clouds. The star bore 265.0°T at a sextant altitude (hs) of 62°25.4'. The chronometer read 11h 24m 39s and is 5m 08s slow. The index error is 1.0' off the arc, and the height of eye is 52 feet. What star did you observe?
Official USCG Answer & Rule Citation
Correct Answer: Option C — Dschubba
Determine the GHA and Declination of the star using the Nautical Almanac for the corrected GMT. Calculate the computed altitude (Hc) and azimuth (Zn) using the Law of Cosines or the Sight Reduction Tables (Pub. 229). Comparing the observed bearing and altitude identifies Dschubba as the correct celestial body.
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