# absolute magnitude

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## absolute magnitude:

see magnitudemagnitude,
in astronomy, measure of the brightness of a star or other celestial object. The stars cataloged by Ptolemy (2d cent. A.D.), all visible with the unaided eye, were ranked on a brightness scale such that the brightest stars were of 1st magnitude and the dimmest stars
.

See magnitude.

## absolute magnitude

[′ab·sə‚lüt ′mag·nə·tüd]
(astrophysics)
A measure of the brightness of a star equal to the magnitude the star would have at a distance of 10 parsecs from the observer.
The stellar magnitude any meteor would have if placed in the observer's zenith at a height of 100 kilometers.
(mathematics)
The absolute value of a number or quantity.
References in periodicals archive ?
If it is assumed that interstellar extinction is negligible then the surface brightness and absolute magnitude of NGC 6210 can be determined.
Once thought to be as much as 9,000 light-years away, Phi may be only 5,000 --and yet still have an absolute magnitude of -7.
The authors are grateful for the assistance given by Gerard Faure and John Greaves in the preparation of this paper: John for his analysis of LONEOS and 2MASS data and drawing our attention to the formula for the calculation of V magnitude, and Gerard for his encouragement in developing the methodology and suggesting its applicability to measurement of the absolute magnitudes of asteroids.
Thus astronomers created the absolute magnitude scale.
Representing the entire range of absolute magnitudes of the stars on these charts, from +6 to -8, proved difficult.
The galaxies M31 and M51 have absolute magnitudes of -21 each.
Most of the stars on this type of chart have absolute magnitudes around zero, and of these most are either main-sequence stars of spectral type A or giants of spectral type G5 through K5.
Distances can be measured by finding the apparent magnitudes of a large sample of a galaxy's cluster population and comparing them with the expected absolute magnitudes.
All RR Lyrae variables have nearly the same absolute magnitude, so they are especially useful as distance indicators.
Instead, we can use the formula to relate the asteroid's size to its so-called absolute magnitude, H, defined as the object's brightness if it were seen 1 a.
The program computes a phase angle of 46|degrees~ and an absolute magnitude of 21.

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