On 25 August your 0300 zone time DR position is LAT 21° 28.0' N, LONG 167° 48.0' E. You are on course 248° T at a speed of 12 knots. You observed 3 celestial bodies. Determine the latitude and longitude of your 0600 running fix. ZONE OBSERVED BODY TIME GHA ALTITUDE (Ho) DECLINATION ------------------- -------- ------------- ------------ --------------- Rigel 0512 167° 31.4' 51° 37.7' S 8° 13.2' Diphda 0518 236° 46.1' 31° 52.1' S 18° 05.2' Acamar 0524 204° 33.0' 27° 40.9' S 40° 22.5'
• Running fix using multiple celestial LOPs (lines of position) advanced to a common time • Effect of course and speed from 0300 to each sight time and then to 0600 on the DR track • Relationship between intercept direction (toward/away) and the shift of your estimated position relative to DR
• From the 0300 DR, where will your DR position be at 0512, 0518, 0524, and 0600 if you maintain course 248°T at 12 knots? • How does applying intercepts for southern stars (all three have south declination) at low to moderate altitudes generally affect your latitude when you are in the northern hemisphere? • Once you advance each LOP to 0600, does your final fix end up north/south and east/west of the 0600 DR, and which of the answer choices is consistent with that overall shift?
• Compute and sketch the 0600 DR position from the given 0300 DR, course, and speed before touching the sights • Make sure your LOPs are correctly advanced along the DR track from each sight time to 0600, not along the perpendicular • Compare each answer’s latitude and longitude to your 0600 DR to see which one matches the direction and approximate size of your total intercept pattern
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