At 2231 ZT on 14 July you are in DR position LAT 34°06' S, LONG 149°47' W, when you observe an amplitude of Jupiter. The planet is about one Sun's diameter above the visible horizon and bears 257.1°psc. The variation is 15°E. What is the deviation?

Correct Answer: Option B — 2.5°W

Amplitude calculations for planets utilize the Nautical Almanac to find the body's declination and latitude. Apply variation to the calculated true amplitude to establish the magnetic bearing, then determine gyro or compass deviation from the observed reading.