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Amplitude of the Sun, Continued
Finding
Amplitude of
the Sun Using
the Celestial
Horizion,
continued
With the amplitude properly labeled, we can now follow another set of
rules to determine the azimuth.
Rules:
1. Rising Sun with north declination, subtract the amplitude from 090°
2. Rising Sun with south declination, add the amplitude to 090°
3. Setting Sun with north declination, add the amplitude to 270°
4. Setting Sun with south declination, subtract the amplitude from 270°
By following the rules above, our amplitude can now be converted to an
azimuth as follows:
W31.2°N + 270° = 301.2°
Our true bearing to the Sun was 300°. Gyro error can be determined as
follows:
301.2° (azimuth)
300.0° (gyro bearing)
1.2 °E (gyro error)
We find the name of the error by using our memory aid
Gyro least - error EAST, Gyro best - error WEST.
Finding
If the body is observed when its center is on the visible horizon, a
Amplitude Using correction from table 28 of Bowditch, Volume II, is applied to the value
the Visible
Horizion
taken from Bowditch’s table 27. Refer to table 28 for step-by-step
instructions.
9-15
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