Abstract:
Photoelectric Johnson UBV and Cousins RI multiaperture photometry of 38 galaxies, 30 of which display outer rings and pseudorings of the R1, R1', R1R2', and R2' types, is presented. The photometry was acquired for the dual purpose of providing precise total magnitudes and colors for a sample of these objects and for serving as zero point calibration data for a set of CCD images described in a separate paper. The integrated colors are consistent with the early Hubble types (S0/a-Sb) characteristic of these kinds of galaxies. Good agreement is found between the integrated photoelectric magnitudes, B(T), and those based on photographic surface photometry in the ESO-LV database. However, the integrated R-band magnitudes, R(T), and the integrated photoelectric colors, (B-R)T, which we provide here are much more precise than those given for the same galaxies in the LV database. The problem appears to be due in part to a systematic error in the LV total R-band magnitudes. The precision of individual measurements in our new dataset is judged by examining the residuals about standard integrated magnitude and color curves following the precepts outlined in the Third Reference Catalogue of Bright Galaxies. From these residuals, we estimate the internal errors of the new photometry to be 0.04, 0.02, 0.05, 0.01, and 0.02 mag for B, B-V, U-B, V-R, and V-I, respectively. We also discuss the derivation of integrated colors (V-R)T and (V-I)I(T) using standard color curves that were previously applied in the Second and Third Reference Catalogues of Bright Galaxies only to UBV data.
