On 28 May your 0200 DR position is LAT 19°16.5' S , LONG 119°24.0' W. You are on course 107°T at a speed of 18 knots. You observed 3 celestial bodies. Determine the latitude and longitude of your 0600 running fix. Body Zone Time GHA Observed Declination Altitude Diphda 0524 076°20.5' 50°34.8' S 18°05.4' Antares 0530 201°26.0' 14°16.9' S 26°23.4' Deneb 0538 140°18.4' 22°00.3' N 45°12.6'
• Running fix with three celestial LOPs – where are the lines of position actually taken, and how are they advanced to the common time? • Relationship between DR (dead reckoning) track and the final fix – compare your 0600 DR with the possible answers. • Effect of course and speed over time on your position between 0200, each sight time, and 0600.
• First, compute how far and in what direction you travel from 0200 to 0600 using the given course and speed. What is your 0600 DR position before applying any sights? • Think about when each LOP (line of position) is actually obtained (0524, 0530, 0538). In a running fix, what do you do to bring all three LOPs to the common time of 0600? • After plotting/advancing the LOPs, where does the combined fix lie relative to your 0600 DR – slightly ahead/astern, to port/starboard? Which choice best matches that shift?
• Be sure your total run from 0200–0600 is correct: distance in nautical miles and track direction. • Check that each LOP is advanced or retired along the track only by the amount run between the sight time and 0600. • Before picking an answer, compare all four choices to your 0600 DR: which one is displaced from the DR in the same direction and by a reasonable amount based on your intercepts?
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