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hour circle

hour circle, in astronomy, a secondary axis in the equatorial coordinate system. The hour circle of a celestial body is the great circle on the celestial sphere that passes through both the body and the north celestial pole. A star's hour circle is used in determining its right ascension and declination.

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.

More on hour circle from Fact Monster:

  • declination - declination declination, in astronomy, one of the coordinates in the equatorial coordinate system. ...
  • right ascension - right ascension right ascension, in astronomy, one of the coordinates in the equatorial coordinate ...
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