RUDE STARFINDER
STAR IDENTIFICATION
As a navigator, you might be asked to obtain a fix from two or more stars. You may wonder how anyone except an astronomer can distinguish one star from the other. Actually, only a few of the multitudes of stars are used regularly for celestial navigation, and they are not too difficult to locate and identify. No matter where you may be navigating, you can manage very well if you are able to recognize 20 or so. The Nautical Almanac, states 57 principal stars as well as tables for finding latitude by the North Star (Polaris).
Relative brightness of stars is called their magnitude; the lower the magnitude, the brighter the star. Sirius, brightest of them all, has a magnitude of - 1.6; Acamar, dimmest of the navigational stars, is listed at + 3.1 magnitude:
First magnitude stars range from magnitude - 1.6 to magnitude +1.50. Second magnitude stars are those from +1.51 to +2.50.
Stars of third magnitude range from +2.51 to +3.50, and so on. Stars of the sixth magnitude are barely visible to the unaided eye.
The magnitudes given here of principal stars are only a fraction of the navigational celestial bodies. Selected navigational planet magnitudes vary due to atmospheric conditions. Mars magnitude, for example, varies from + 1.6 to -2.8. The moon usually has a magnitude of
12.6; however, its "phase" must be considered prior to use. The king of celestial bodies, with a magnitude of -26.7, is the sun, limited only by nighttime and atmospheric conditions. The magnitude of the planets is listed at the top of daily pages and stars at the end of the white pages in the Nautical Almanac.
Man's imagination has given fanciful names to various groups of the brighter stars. The stars of each of these groups are said to form a constellation. Constellations are named according to objects they are thought to resemble in outline. Orion, the hunter, with his belt and sword, is a good example.
One or more of the stars in a constellation may be navigational stars. Obviously, if you can recognize a constellation and know which of its stars may be used, you can identify them ,when ever the group is visible in the sky. The constellation familiarly called the Big Dipper (from a striking resemblance to a dipper with a handle) is known to astronomers as Ursa Major or Great Bear. Its resemblance to a bear puts considerable strain on the imagination, but the
