On 8 April while taking observations for an evening fix, you observe an unidentified star bearing 250.7°T at an observed altitude of 51°44.8'. Your DR position at the time of the sight was LAT 22°16.0' N, LONG 157°58.3' W. The chronometer reads 05h 09m 57s and is 01m 23s slow. What star did you observe?
• Using the chronometer error (slow/fast) to find the correct GMT of the sight • Relating DR position, true bearing, and observed altitude to identify a star on the star finder or in sight reduction tables • How LHA Aries and GHA/Dec of stars help distinguish between stars with similar bearings and altitudes
• How do you correct the chronometer reading when it is 01m 23s slow to get the correct UTC at the time of the sight? • Once you know the exact time and your DR longitude, what is your Local Hour Angle and which stars should be close to bearing 250°T and altitude about 52° from your latitude? • Among the four candidate stars, which one’s declination and hour angle best match an altitude of about 52° from latitude 22°N and a westerly (SW) bearing?
• Be sure you apply the chronometer error in the correct sense (slow vs fast) when finding UTC • Confirm that the computed bearing and altitude for your chosen star are both close to the observed 250.7°T and 51°44.8' • Verify that the star’s declination makes sense for being that high in the sky from 22°N at evening twilight in early April
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