On 12 June your 1845 DR position is LAT 21°47'N, LONG 46°52'W when you observe a faint unidentifiable star through a break in the clouds. The star bears 282.5°T at a sextant altitude (hs) of 14°22.3'. The index error is 0.5'on the arc, and the height of eye is 45 feet. The chronometer reads 09h 43m 27s, and the chronometer error is 1m 46s slow. What star did you observe?

Question

On 12 June your 1845 DR position is LAT 21&deg;47'N, LONG 46&deg;52'W when you observe a faint unidentifiable star through a break in the clouds. The star bears 282.5&deg;T at a sextant altitude (hs) of 14&deg;22.3'. The index error is 0.5'on the arc, and the height of eye is 45 feet. The chronometer reads 09h 43m 27s, and the chronometer error is 1m 46s slow. What star did you observe?

Accepted Answer

Option B: Alhena. Convert chronometer time to GMT, determine GHA Aries, and find the star's SHA. Calculate LHA and Declination to plot the celestial position. Comparing these coordinates against the Nautical Almanac star list confirms Alhena as the observed body, consistent with the measured altitude and bearing provided in the problem.