On 2 April your 0830 zone time fix gives you a position of LAT 20°16.0'S, LONG 004°12.0'E. Your vessel is steaming a course of 143°T at a speed of 18.0 knots. An observation of the Sun's upper limb is made at 0903 zone time, and the observed altitude (Ho) is 42°39.6'. The chronometer reads 09h 05m 40s, and the chronometer error is 02m 15s fast. Local apparent noon occurs at 1145 zone time, and a meridian altitude of the Sun's lower limb is made. The observed altitude (Ho) for this sight is 63°46.2'. Determine the vessel's 1200 zone time position.

Question

On 2 April your 0830 zone time fix gives you a position of LAT 20&deg;16.0'S, LONG 004&deg;12.0'E. Your vessel is steaming a course of 143&deg;T at a speed of 18.0 knots. An observation of the Sun's upper limb is made at 0903 zone time, and the observed altitude (Ho) is 42&deg;39.6'. The chronometer reads 09h 05m 40s, and the chronometer error is 02m 15s fast. Local apparent noon occurs at 1145 zone time, and a meridian altitude of the Sun's lower limb is made. The observed altitude (Ho) for this sight is 63&deg;46.2'. Determine the vessel's 1200 zone time position.

Accepted Answer

Option C: LAT 21&deg;18.0'S, LONG 005&deg;00.5'E. Calculate the latitude at LAN using the meridian altitude formula. Advance the 0903 ZT sun line to the 1200 ZT position using the run between sights. The intersection of the advanced line and the meridian latitude yields the final position of 21°18.0'S, 005°00.5'E, consistent with standard celestial navigation procedures.