Transformation algorithm

American Association of Variable Star Observers (AAVSO)
Mon, 03/16/2015 - 22:31

In order to apply a transformation correction for V in the B-V system, it is necessary to know delta(B-V) for the variable/comparison pair.  I'm interested to know how VPHOT determines delta(B-V) from the instrumental b and v magnitudes.  I derived a formula for this from Photoelectric Photometry of Variable Stars (Hall and Genet), and I'm very curious to see how it compares.