On 19 November your 0200 zone time DR position is LAT 20°29.0' N, LONG 150°21.3' E. You are on course 136°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 Regulus 0530 198°24.3' 77°21.3' N 12°03.4' Arcturus 0532 137°03.2' 22°47.9' ' N 19°16.7 Suhail 0537 215°10.4' 26°44.9' S 43°21.2'
• Running fix and how to advance LOPs (Lines of Position) using DR track between observation time and fix time • Converting zone time to GMT (UTC) and using GHA (Greenwich Hour Angle) and declination to get GP (geographical position) of each star • How the DR track from 0200 to 0600 (course 136°T, speed 18 knots) will shift your estimated latitude and longitude
• First, compute the DR position at 0530–0537 and at 0600 from the 0200 DR position, given course and speed. How far and in what direction have you moved by each time? • Think about whether the running fix position should be ahead of or behind the 0600 DR along your track, and whether it should be slightly more east/west or north/south compared to the DR. • Compare the answer choices to your 0600 DR position. Which latitude/longitude pairs best match a small correction that would come from 3-star LOPs intersecting near your DR?
• Be sure your DR advance calculation from 0200 to 0600 uses: distance = speed × time (in hours) along course 136°T. • Check whether the longitudes in the choices are east of or west of your 0600 DR longitude, based on your track and expected sights. • Verify that your chosen answer lies reasonably close (within a few miles) to the 3-star fix you’d expect from sights taken around 0530–0537, advanced to 0600.
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