An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

   Homepage   
    


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Number of Results: 1 Search : UBV system
UBV system
  راژمان ِ UBV   
râžmân-e UBV

Fr.: système photométrique UBV   

A → photometric system which consists of measuring an object's → apparent magnitude through three broad-band filters: the ultraviolet (U) at 3650 Å, the blue (B) at 4400 Å, and the visual (V) in the green-yellow spectral region at 5500 Å. The filter bandwidths are 680, 980, and 890 Å respectively. The system is defined so that for A0 stars B - V = U - B = 0. The system was devised by Harold Johnson (1921-1980) and William Morgan (1906-1994) at Yerkes Observatory. It was extended to the R and I bands centered at 7000 and 9000 Å respectively and later to other infrared bands.

U, B, and V referring to "ultraviolet," "blue," and "visible" respectively; → system.