annual parallax

Definitions

  • WordNet 3.6
    • n annual parallax the parallax of a celestial body using two points in the earth's orbit around the sun as the baseline
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Webster's Revised Unabridged Dictionary
    • Annual parallax the greatest value of the heliocentric parallax, or the greatest annual apparent change of place of a body as seen from the earth and sun; it is equivalent to the parallax of an astronomical object which would be observed by taking observations of the object at two different points one astronomical unit (the distance of the Earth from the sun) apart, if the line joining the two observing points is perpendicular to the direction to the observed object; as, the annual parallax of a fixed star. The distance of an astronomical object from the Earth is inversely proportional to the annual parallax. A star which has an annual parallax of one second of an arc is considered to be one parsec (3.26 light years) distant from the earth; a star with an annual parallax of one-hundredth second of an arc is 326 light years distant. See parsec in the vocabulary, and stellar parallax, below.
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Usage

In literature:

It is improbable, however, that even these nearer stars are practicable subjects for the direct determination of annual parallax.
"Scientific American Supplement, No. 623, December 10, 1887" by Various
The annual parallax of a star is the angle under which one would see the radius, or half-diameter, of the terrestrial orbit from it.
"Astronomy for Amateurs" by Camille Flammarion
We have also ascertained that the annual parallax is about half a second.
"The Story of the Heavens" by Robert Stawell Ball
The annual parallax of a heavenly body is the angle subtended at that body by the radius of the Earth's orbit.
"The Astronomy of Milton's 'Paradise Lost'" by Thomas Orchard
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In science:

All parameters” means that about the same accuracy is obtained for annual proper motions, positions and parallaxes, as was in fact achieved with Hipparcos, for the first time in the history of astronomy.
Astrometry during the past 2000 years
Hipparcos 1 mas at 1991 Hipparcos obtained the median accuracy of 1 mas for positions, annual proper motions and parallaxes of 120 thousand stars.
Astrometry during the past 2000 years
The median accuracy for parallaxes and annual proper motions of the 1200 million stars in the final Gaia catalogue is expected to be about 180 microarcsec, much better than the accuracy of Hipparcos.
Astrometry during the past 2000 years
More now from Bessel : Bessel (1838) explains his observations and reductions and gives first the annual parallax derived from the star a at 8' distance and from star b at 12'. They are respectively 0.3690” +-0.0283” and 0.2605” +-0.0278”. The combined solution from a and b gives 0.3136” +-0.0202”.
Astrometry during the past 2000 years
All parameters” means that about the same accuracy is obtained for annual proper motions, positions and parallaxes, as was in fact achieved with Hipparcos, for the first time in the history of astronomy.
Astrometry during the past 2000 years
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