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 68°03.6' bearing 154°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 68&deg;03.6' bearing 154&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 D: Alpha Indi. Calculate the Greenwich Hour Angle (GHA) and Declination (Dec) using the Nautical Almanac for the given GMT. Determine the Local Hour Angle (LHA) by applying longitude. Comparing the computed LHA and Dec against the Sight Reduction Tables (Pub. 249 or 229) identifies Alpha Indi as the celestial body.