单词 | UBV system |
释义 | UBV system [¦yü´bē¦vē ´sis·tǝm] 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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