Latitude by Polaris

Latitude by Polaris is a quick reduction that gives the observer’s latitude from a single altitude of the pole star, since Polaris sits within about 0.7 degrees of the north celestial pole. The Nautical Almanac Polaris tables give three corrections: latitude equals Ho minus 1 degree plus a0 plus a1 plus a2, where a0 depends on LHA Aries, a1 on latitude, and a2 on the date. The subtracted 1 degree and the added corrections together account for Polaris not lying exactly on the pole. The same tables also yield the azimuth of Polaris for a compass check. The method works only in the northern hemisphere.