On 17 December your 0600 ZT fix gives you a position of LAT 27°16.7'N, LONG 138°39.2'W. Your vessel is on course 137°T, and your speed is 14.8 knots. Local apparent noon (LAN) occurs at 1207 ZT, at which time a meridian altitude of the Sun's lower limb is observed. The observed altitude (Ho) for this sight is 40°22.1'. What is the calculated latitude at LAN?

Question

On 17 December your 0600 ZT fix gives you a position of LAT 27&deg;16.7'N, LONG 138&deg;39.2'W. Your vessel is on course 137&deg;T, and your speed is 14.8 knots. Local apparent noon (LAN) occurs at 1207 ZT, at which time a meridian altitude of the Sun's lower limb is observed. The observed altitude (Ho) for this sight is 40&deg;22.1'. What is the calculated latitude at LAN?

Accepted Answer

Option D: 26&deg;15.4'N. Meridian altitude calculation requires finding the Sun's declination from the Nautical Almanac for the time of LAN. Using the formula Latitude = (90° - Ho) ± Declination, where Ho is corrected for dip and refraction, the calculated latitude at 1207 ZT is 26°15.4'N, consistent with standard celestial reduction procedures.