Declination (dec)

Declination is the celestial-sphere analogue of latitude: the angular distance of a body north (+) or south (-) of the celestial equator, from 0 to 90 degrees. With Greenwich Hour Angle it fixes a body’s position on the sphere, and the Nautical Almanac tabulates both hourly for the Sun, Moon, planets, and Aries, plus declination for the 57 stars. Declination enters the astronomical triangle as the polar distance, 90 degrees minus declination, the side from the pole to the body. When a body crosses the observer’s meridian, latitude follows directly from its declination and meridian altitude.