UBV system

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UBV system

[¦yü‚bē¦vē ‚sis·təm]
(astronomy)
A system of stellar magnitudes in which an object's apparent magnitude is measured at three wavelengths, labeled U, at 360 nanometers; B, at 420 nanometers; and V, at 540 nanometers; and is characterized by the color indices B-V and U-B, which are both defined to be 0 for a star of spectral type A0. Also known as Johnson-Morgan system.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Since the advent of the Johnson UBV photometric system in the 1950s and the replacement of photography by CCD imaging, many clusters have been re-measured so most clusters in WEBDA now have UBV data.