The UcBV photometric system

Basic Reference

Arp H.C. 1958, AJ 63, 118


Aproximately 290 three-color measures on 170 stars in the southern hemisphere are reported. The measures are of Johnson-Morgan standards, E-region standards, southern supergiants, and sequences in the Small Magellanic Cloud, Large Magellanic Cloud and omega Centauri. Magnitudes are given on the B, V system; the range of brightness is from V = 1 to 13 mag.

The measures were obtained with the 24-inch refracting telescope of the Royal Observatory. The ultraviolet color indices obtained with that refractor are calibrated in terms of reddening and luminosity class. Preliminary results on six Small Magellanic Cloud supergiants are given.


Access to the data and references

Asiago Database on Photometric System (ADPS)

Indices and Parameters

V, B-V, Uc-B


   Uc : 2 mm Corning 9863
   B  : 2 mm Schott GG13 + 2 mm BG12
   V  : 2 mm Omag 302

Transmission curves

Reddening-free Parameter

Q = (U-Bc) - 0.36 (B-V)




In the course of a systematic comparison of photometric data, a number of problems have been found, but could not be solved. Generally the data associated with a star identification are not in agreement with those from other systems, usually the UBV system.
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Last update: 21 May 1996