On 15 February at 0610 ZT, in DR position LAT 56°53.0' N, LONG 157°02.9' E, you observe Polaris at a sextant altitude (hs) of 56°10.4'. The index error is 2.5' on the arc, and the height of eye is 18 meters. What is the latitude?

Correct Answer: Option A — 56°41.8'N

Correcting sextant altitude for index error (on the arc, subtract) and dip derived from an 18-meter height of eye provides apparent altitude. Applying refraction and the Nautical Almanac Polaris tables (tabular corrections a0, a1, a2) based on local hour angle of Aries yields LAT 56°41.8'N.