Nautical Almanac

The Nautical Almanac is the annual volume produced jointly by HM Nautical Almanac Office and the US Naval Observatory that supplies the positional data for marine celestial navigation. Daily pages tabulate hourly GHA and declination of the Sun, Moon, and four navigational planets, GHA of Aries, and the SHA and declination of 57 selected stars, all in GMT (UT). The yellow increments-and-corrections pages interpolate for minutes and seconds. The back carries altitude-correction tables, the Polaris tables, twilight and rise/set data, and the standard reduction examples. It is the single book a navigator needs at the chart table beyond the sextant and a watch.