On 2 October your 1845 DR position is LAT 28°09.2'S, LONG 167°48.1'E. You observe a faint star through a hole in the clouds at a sextant altitude (hs) of 25°19.4' bearing 273°T. The index error is 1.3' off the arc, and the height of eye is 42 feet. The chronometer reads 07h 46m 19s and is 0m 51s fast. What star did you observe?

Question

On 2 October your 1845 DR position is LAT 28&deg;09.2'S, LONG 167&deg;48.1'E. You observe a faint star through a hole in the clouds at a sextant altitude (hs) of 25&deg;19.4' bearing 273&deg;T. The index error is 1.3' off the arc, and the height of eye is 42 feet. The chronometer reads 07h 46m 19s and is 0m 51s fast. What star did you observe?

Accepted Answer

Option C: Beta Librae. Correct the sextant altitude for index error (off the arc is additive) and dip. Calculate GHA Aries and the star's SHA to find the LHA. Comparing the resulting LHA and Declination against the Nautical Almanac star list identifies Beta Librae, consistent with the observed altitude and bearing.