At 1502 ZT on 4 August, in DR position LAT 11° 21.6'S, LONG 088° 14.3'E, you observe an amplitude of the Moon. The upper limb of the Moon is on the visible horizon and bears 289° psc. The variation is 15°W. What is the deviation?

Question

At 1502 ZT on 4 August, in DR position LAT 11&deg; 21.6'S, LONG 088&deg; 14.3'E, you observe an amplitude of the Moon. The upper limb of the Moon is on the visible horizon and bears 289&deg; psc. The variation is 15&deg;W. What is the deviation?

Accepted Answer

Option B: 1.1&deg;W. Celestial amplitude calculations for the Moon's upper limb require applying semi-diameter corrections to find the true azimuth. Comparing the resulting true bearing against magnetic and compass readings using variation (15°W) resolves the standard compass deviation as 1.1°W.

At 1502 ZT on 4 August, in DR position LAT 11&deg; 21.6'S, LONG 088&deg; 14.3'E, you observe an amplitude of the Moon. The upper limb of the Moon is on the visible horizon and bears 289&deg; psc. The variation is 15&deg;W. What is the deviation?

At 1502 ZT on 4 August, in DR position LAT 11° 21.6'S, LONG 088° 14.3'E, you observe an amplitude of the Moon. The upper limb of the Moon is on the visible horizon and bears 289° psc. The variation is 15°W. What is the deviation?