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.

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References in periodicals archive ?

(7.) Mermilliod JC: Photoelectric Photometric Catalogue of Homogenous Measurements in the UBV system. NASA, Astronomical Data Center, Selected Astronomical Catalogues.

Wideband Photometry of Saturn in 2008-2009

Photometry measured on the Johnson UBV system on the nights of 12, 25 and 26 July 1978 with the 0.5 and 1.0-m reflectors at Sutherland has yielded V= 12.68, B-V= +1.31, U-B= + 1.00.

From the impossible to the possible: Magda Streicher--Presidential Address 2008

So successful was the UBV system that it was extended redward with R and I filters to define standard red and near-infrared magnitudes.