Celestial Navigation · Longitude
An error of 4 seconds in the time of a sight introduces an error in longitude of about:
- A1 minute of arc✓ Correct
- B1 degree
- C4 degrees
- DZero
Explanation
The Earth turns 15° per hour, i.e., 1° in 4 minutes and 1' of arc in 4 seconds of time. Hence accurate timekeeping is critical to celestial longitude.
Authority: Bowditch (Pub. No. 9), time and longitude
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
- 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:
- The Nautical Almanac
Approximately how fast does the GHA of the Sun increase with time?