Because some WD V-mag's from the catalogs are
wildly inaccurate (e.g., WD2256+313, as pointed out by Ayiomamitis),
I have adopted a new procedure for assigning V-mag's. I'll
use UCAC3 "aperture" mag's (passband between V & R) that are
modified using: Vucac3
= 0.69 + 0.925 × UCAC3 + 0.582 × (J-K),
SE = 0.073 mag, N=92. This equation
was inspired by a poster by Joe Garlitz, which in turn was probably
inspired by work by Pavlov, showing that such an equation was
possible. My coefficients are based on the 92 standard stars that
have Landolt, SDSS and UCAC3 mag's. I tried additional terms (such
as using the SuperCOSMOS mag's, and higher powers of J-K), but the
simple equation above was the winner. My coefficients are similar to
the results of Garlitz, and also Pavlov, and all of us get a similar
RMS. I will use the term Vucac3 on PAWM web pages to indicate
that I've adopted this version of V-mag.
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