On 17 April your vessel's 1856 zone time DR position is LAT 22°35.0'N, LONG 63°15.0'W. At that time, a sextant observation of the star Sirius is made. The sextant altitude is 42°45.0' and the chronometer reads 10h 59m 27s. The index error is 2.6' off the arc, and the chronometer error is 03m 01s fast. Your height of eye is determined to be 45 feet. What is the computed altitude (Hc) and azimuth (Zn) for this sight using the assumed position?

Question

On 17 April your vessel's 1856 zone time DR position is LAT 22&deg;35.0'N, LONG 63&deg;15.0'W. At that time, a sextant observation of the star Sirius is made. The sextant altitude is 42&deg;45.0' and the chronometer reads 10h 59m 27s. The index error is 2.6' off the arc, and the chronometer error is 03m 01s fast. Your height of eye is determined to be 45 feet. What is the computed altitude (Hc) and azimuth (Zn) for this sight using the assumed position?

Accepted Answer

Option C: 42&deg;51.6', 214.9&deg;T. Per Bowditch celestial navigation guidelines, correct chronometer time for GMT, extract Greenwich hour angle and declination for Sirius, apply index error and dip, and solve the navigational triangle using the assumed position to find Hc and Zn.