[vsnet-chat 2508] B-V to V-R

[Brian Skiff <bas@lowell.edu>]

     A simple regression against colors of Landolt stars yields:

(V-R) = 0.508(B-V) + 0.040

or:  R = V - 0.508(B-V) - 0.040

Note that the sign difference on the zero-point is opposite what Arne posted,
which was my arithmetic error, not his.  This relation works quite well
for stars bluer than B-V = 1.2.  More complex functional forms were derived
by John Caldwell and published in the South African Astronomical OBservatory
Circulars a few years ago.  These cover all the UBVRIJHK, uvby, and DDO
colors with extended range in color space.

\Brian

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