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right ascension

noun, Astronomy.
the arc of the celestial equator measured eastward from the vernal equinox to the foot of the great circle passing through the celestial poles and a given point on the celestial sphere, expressed in degrees or hours.
Origin of right ascension
First recorded in 1585-95 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for right ascension
Historical Examples
  • It is the sum or difference of the right ascension and ascensional difference.

    The Sailor's Word-Book William Henry Smyth
  • This motor governs the hour motion, that one the right ascension.

    Skylark Three Edward Elmer Smith
  • We call A the right ascension of the apex; D its declination.

  • Motion in longitude is not the same thing as motion in right ascension.

  • A is the right ascension of the star, and U is the correction of the clock.

    A Text-Book of Astronomy George C. Comstock
  • Now (Dec. 3) it has south declination of 34, and right ascension of 19h.

  • Declination about minus twenty, as I remember it, and right ascension between six and seven hours.

    Skylark Three Edward Elmer Smith
  • As he gives her the word, she writes down the declination and right ascension, and the other circumstances of the observation.

    Pioneers of Science Oliver Lodge
  • The two apices differ very nearly 180° in right ascension and about 120° in declination.

    Curiosities of the Sky Garrett Serviss
  • First there will be the star's name, and in the next column its magnitude, and in a third the star's right ascension.

    Astronomy David Todd
British Dictionary definitions for right ascension

right ascension

(astronomy) the angular distance measured eastwards along the celestial equator from the vernal equinox to the point at which the celestial equator intersects a great circle passing through the celestial pole and the heavenly object in question α Compare declination (sense 1)
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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right ascension in Science
right ascension  
The position of a celestial object east of the vernal equinox along the celestial equator. Right ascension is measured in hours, minutes, and seconds from the vernal equinox (0 hours) to the point where a great circle drawn through the object and the north and south celestial poles intersects the celestial equator. Each hour corresponds to 15° of angular distance along the celestial equator for a total of 24 hours. See more at equatorial coordinate system.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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