Celestial Navigation · Amplitudes — Compass Error
You observe the sun's amplitude at sunrise as 074° per gyrocompass; the computed true bearing is 068.5°T. What is the gyro error?
- A5.5°E
- B5.5°W (gyro reads high)✓ Correct
- C2.0°W
- DNo error
Explanation
Gyro error = true − gyro = 068.5° − 074° = −5.5°. Because the gyro reads higher than true ('gyro best, error west'), the error is 5.5°W. Amplitude observations near the horizon are a standard way to check compass error at sunrise/sunset.
Authority: Bowditch (Pub. No. 9), amplitude observation for compass error
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
- Amplitudes — Compass Error
A body's computed true amplitude gives a rising bearing of 064°T. You observe it rise on a compass bearing of 060°. What is the compass error?
- 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: