Celestial Navigation · Meridian Altitude — LAN Timing
Latitude by meridian altitude of the sun is taken at the moment of:
- ACivil twilight
- BLocal apparent noon, when the sun crosses the observer's meridian and reaches maximum altitude✓ Correct
- CGreenwich mean noon regardless of longitude
- DThe instant the sun's GHA equals 0°
Explanation
At local apparent noon (LAN) the sun is on the observer's meridian at its greatest altitude, so it bears due north or south. The meridian-altitude latitude sight requires no exact time and no sight-reduction tables — only the corrected altitude and declination.
Authority: Bowditch (Pub. No. 9), meridian altitude; the day's work
Practice the full Celestial Navigation bank
Free spaced-repetition quizzing across 2190 USCG exam questions — it schedules your reviews so the ones you miss come back until they stick.
Related Celestial Navigation questions
- Meridian Altitude — LAN Timing
Local apparent noon (LAN) occurs at the moment the sun:
- Time
The Nautical Almanac tabulates the positions of celestial bodies against which time standard?
- Time
A vessel in west longitude has a zone description of +5. To convert zone time to UT you must:
- Coordinates
How is the GHA of a star obtained from the Nautical Almanac?
- Coordinates
Sidereal Hour Angle (SHA) is best defined as:
- Coordinates
Declination of a celestial body is the celestial equivalent of: