2008AJ....136.1546J

New South African Astronomical Observatory (SAAO) BV(RI)_Cmeasurements of 19 Hyades stars and 11 M67 stars are reported. The zero points of the new color indices conform closely to those of SAAO data reported in a previous paper. In addition, the new M67 measurements of (V - R)_C and (R - I)_C are compared to data published previously by Taylor, Joner, and Jeffery. The results support conclusions drawn by those authors that the scale factors of their data are correct and that a scale factor problem exists in measurements published by Montgomery, Marshall, and Janes. The new values of B - V are used with Tycho data in tests of extant Hyades and M67 measurements and of the accuracy of the SAAO B - V system. A problem encountered previously with the Hyades B - V zero point is resolved, and an extant Hyades relation between B - V and (R - I)_C is re-zeroed. A satisfactory zero point is also obtained for M67, and published photomultiplier values of B - V are reduced to that zero point, averaged, and tabulated. It is found that the zero point of B - V data published by Sandquist is satisfactory. However, tests of B - V measurements made by Montgomery et al. suggest that those data are not on a single zero point. Finally, the scale factor of the E region B - V system is found to be satisfactory, but a well-supported interim conclusion is drawn that E region values of B - V should be corrected by about -9 mmag. It is suggested that this conclusion be tested by using instrumental systems that have not yet contributed to the testing process.