Definition
Since the stars keep essentially constant positions relative to each other, each navigational star is given an SHA and a declination that change only slowly through the year. The almanac lists both for 57 selected stars. Star GHA equals SHA plus GHA of Aries. Arcturus, for instance, has an SHA near 146 degrees; the exact value drifts by a fraction of a minute of arc over a season, so the current almanac must be used.
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