On 27 June your 1905 ZT DR position is LAT 24°35.0'N, LONG 50°15.0'W. At that time, you observe Saturn bearing 211°pgc. The chronometer reads 10h 04m 26s and the chronometer error is 01m 20s slow. The variation is 4.5°E. What is the gyro error?

Correct Answer: Option B — 1.1°W

Calculate the LHA of Saturn using the chronometer time and DR longitude. Use the amplitude formula or azimuth tables to find the true bearing. Compare the true bearing to the gyro bearing (211°pgc) to determine the gyro error. The difference between the two values yields the 1.1°W gyro error.