On 1 July your 0515 ZT fix gives you a position of LAT 24°36.0'S, LONG 151°42.0'W. Your vessel is on course 300°T, and your speed is 10.0 knots. Local apparent noon (LAN) occurs at 1215 ZT, at which time a meridian altitude of the Sun's lower limb is observed. The observed altitude (Ho) for this sight is 42°55.0'. What is the calculated latitude at LAN?

Question

On 1 July your 0515 ZT fix gives you a position of LAT 24&deg;36.0'S, LONG 151&deg;42.0'W. Your vessel is on course 300&deg;T, and your speed is 10.0 knots. Local apparent noon (LAN) occurs at 1215 ZT, at which time a meridian altitude of the Sun's lower limb is observed. The observed altitude (Ho) for this sight is 42&deg;55.0'. What is the calculated latitude at LAN?

Accepted Answer

Option C: 24&deg;01.0'S. For a meridian altitude in the Southern Hemisphere, Latitude = (90° - Ho) - Declination (if same name). Using the Nautical Almanac for 1 July, the Sun's declination is applied to the zenith distance. The calculation yields 24°01.0'S, confirming the vessel's position at the time of local apparent noon.