Some comparisons in VSP come up with Rc magnitudes that are from the WBVR system. An example is 000-BCR-325, visible in chart X28636ZM for V509 Cas. This star corresponds to HR 8832 / HD 219134.
I know of no "native" Cousins photometry for this star, but in a 1986 paper (1986ApJS...60..577T ) Taylor quotes a V-Rc conversion from the Argue VRI system as about 0.58. The VSP V-Rc (from Bright Star catalog) is about 0.80, a difference of 0.22.
The R passbands are highly triangular, and the WBVR R band peaks about 70nm redward of Cousins.
I won't claim that Taylor's conversion is exact, or that the V magnitude from Argue and VSP exactly agree, but 0.22 is a large difference. It seems like any star with significant flux near the Cousins peak will register quite differently in the two filters. Should WBVR R data really be in VSP?
Tom
The V-R about 0.8-something for an early-K dwarf is surely (V-R)j rather than (V-R)c. The transformation for V-R in the Kornilov WBVR system (close to Johnson) to Cousins is: (V-R)c = 0.713(V-R)j - 0.005, applicable for all RA, with per-star rms scatter of 0.012 mag. This is from Table 9 in Appendix A of:
https://iopscience.iop.org/article/10.1086/430422/pdf
Anyway, for HD 219134 this yields V-Rc = 0.576 +/- 0.012, obviously competitive with the value derived from the 1966 Johnson value quoted from the 1986 Taylor transformations paper.
I have a copy of the WBVR catalogue if someone wants it.
\Brian
Indeed, the Rc quoted for this star is a Johnson magnitude.