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 148.0°T at a sextant altitude (hs) of 32°24.3'. The chronometer read 11h 24m 39s and is 05m 08s slow. The index error is 1.0' off the arc, and the height of eye is 52 feet. What star did you observe?

Question

On 13 September your 1830 ZT DR position was LAT 23&deg;03'S, LONG 105&deg;16'E, when you observed a faint unidentifiable star through a hole in the clouds. The star bore 148.0&deg;T at a sextant altitude (hs) of 32&deg;24.3'. The chronometer read 11h 24m 39s and is 05m 08s slow. The index error is 1.0' off the arc, and the height of eye is 52 feet. What star did you observe?

Accepted Answer

Option A: Alpha Tucanae. Calculate GHA and Declination using the Nautical Almanac for the observed time. Determine the Local Hour Angle (LHA) by applying longitude. Using the intercept method (Ho vs Hc) and azimuth, compare the calculated coordinates against the star list. Alpha Tucanae matches the computed celestial coordinates for this specific observation time.