On 13 October your 0515 zone time (ZT) fix gives you a position of LAT 26°53.0'N, LONG 90°05.0'W. Your vessel is on course 068°T, and your speed is 7.8 knots. Local apparent noon (LAN) occurs at 1145 zone time, at which time a meridian altitude of the Sun's lower limb is observed. The observed altitude (Ho) for this sight is 54°51.5'. What is the calculated latitude at LAN?

Question

On 13 October your 0515 zone time (ZT) fix gives you a position of LAT 26&deg;53.0'N, LONG 90&deg;05.0'W. Your vessel is on course 068&deg;T, and your speed is 7.8 knots. Local apparent noon (LAN) occurs at 1145 zone time, at which time a meridian altitude of the Sun's lower limb is observed. The observed altitude (Ho) for this sight is 54&deg;51.5'. What is the calculated latitude at LAN?

Accepted Answer

Option A: 27&deg;12.6'N. Meridian altitude sight reduction involves correcting the observed altitude for dip and refraction to obtain Ho. Using the Nautical Almanac for 13 October, the Sun's declination is applied to the zenith distance (90° - Ho). The resulting latitude is 27°12.6'N, following standard Bowditch celestial navigation methodologies.