At 1523 ZT on 14 June, in DR position LAT 31°58'S, LONG 48°42'W you observe an amplitude of the Moon. The center of the Moon is on the visible horizon and bears 118.0°psc. The variation is 10°W. What is the deviation?

Question

At 1523 ZT on 14 June, in DR position LAT 31&deg;58'S, LONG 48&deg;42'W you observe an amplitude of the Moon. The center of the Moon is on the visible horizon and bears 118.0&deg;psc. The variation is 10&deg;W. What is the deviation?

Accepted Answer

Option B: 2.1&deg;W. Calculate the Sun's declination and the observer's latitude to find the amplitude. The formula sin(Amp) = sin(Dec) / cos(Lat) provides the true amplitude. Convert this to a true bearing. With a variation of 10°W, compare the true bearing to the compass bearing of 118.0°psc to find 2.1°W deviation.

At 1523 ZT on 14 June, in DR position LAT 31&deg;58'S, LONG 48&deg;42'W you observe an amplitude of the Moon. The center of the Moon is on the visible horizon and bears 118.0&deg;psc. The variation is 10&deg;W. What is the deviation?

At 1523 ZT on 14 June, in DR position LAT 31°58'S, LONG 48°42'W you observe an amplitude of the Moon. The center of the Moon is on the visible horizon and bears 118.0°psc. The variation is 10°W. What is the deviation?