On 13 September your 1830 ZT DR position was LAT 23°03'S, LONG 105°16'E when you observe a faint unidentifiable star through a hole in the clouds. The star bore 132.3°T at a sextant altitude (hs) of 29°34.6'. 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?

Question

On 13 September your 1830 ZT DR position was LAT 23&deg;03'S, LONG 105&deg;16'E when you observe a faint unidentifiable star through a hole in the clouds. The star bore 132.3&deg;T at a sextant altitude (hs) of 29&deg;34.6'. 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?

Accepted Answer

Option B: Beta Gruis. Correct the sextant altitude for index error (off the arc is additive), dip, and total correction to find Ho. Determine GHA Aries and SHA of the body using the Nautical Almanac. Calculate LHA and declination to identify the star. Beta Gruis matches the calculated coordinates for the given observation time.