1995PASP..107...27J

In this paper, we consider the zero points of six sets of Stromgren-beta photometry. The color-index system to which our results are referred is a "Hyades-Coma" system composed of photometry by Crawford and Perry (1966AJ.....71..206C) and Barnes (1969AJ.....74..407C). For V magnitudes, we use measurements by Taylor and Joner (1992PASP..104..911T). Our results are as follows: (1) The zero points of photometry by Gronbech and Olsen (1976A&AS...25..213G; 1977A&AS...27..443G) are offset from those of the Hyades-Coma system. The offsets can amount to several mmag; they appear for V and all color indices except beta, and depend on right ascension and (usually) declination. (2) These offsets can be applied to photometry by Stetson (1991AJ....102..589S), who reduced his results to the Gronbech-Olsen system. After correction, Stetson's results for a set of "transfer stars" differ from comparable data published by Crawford and Barnes (1970AJ.....75..978C). (3) A direct comparison of the transfer stars to the Hyades yields consistency between the Hyades-Coma and Crawford-Barnes zero points (for the transfer stars specifically). This result supports a conclusion drawn by Taylor and Joner, and suggests that there is some problem with the zero points of Stetson's transfer-star data. (4) From Stetson's corrected data, one finds that the Crawford-Perry zero points for the Hyades are consistent with the Crawford-Barnes zero points for Coma. This result agrees with a conclusion drawn by Taylor and Joner from their own data, and suggests that the problem postulated for Stetson's transfer-star data does not extend to his results for the Hyades and Coma.