color index
- the difference between the apparent photographic magnitude and the apparent visual magnitude of a star.
- the difference between the magnitudes of a star in any two spectral regions.
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Origin of color index
First recorded in 1920–25
Dictionary.com Unabridged
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for color index
Historical Examples
The color-index is thus almost invariably low, the average being about 0.5.
A Manual of Clinical DiagnosisJames Campbell Todd