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hour circle

noun, Astronomy
a great circle on the celestial sphere passing through the celestial poles and containing a point on the celestial sphere, as a star or the vernal equinox.
Also called circle of declination.
1665-75 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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British Dictionary definitions for hour circle

hour circle

a great circle on the celestial sphere passing through the celestial poles and a specified point, such as a star
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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hour circle in Science
hour circle  
A great circle passing through the poles of the celestial sphere and intersecting the celestial equator at right angles. An hour circle is equivalent to a meridian on Earth and is used in describing the position of a celestial body with respect to an observer's celestial meridian. See more at hour angle.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Article for hour circle

in astronomy, any great circle (similar to longitude) on the celestial sphere that passes through the celestial poles-i.e., is perpendicular to the celestial equator. The declination of a celestial object is measured along its hour circle. The hour circle that at any moment is passing through an observer's zenith is his meridian.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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