The peculiar motions of early-type galaxies in two distant regions. III - The photometric data

Abstract

We present R-band CCD photometry for 776 galaxies observed in the EFAR project. The photometry is compared with photoelectric data, showing that a common zero-point good to better than 1 per cent and a precision of 0.03 mag per zero-point have been achieved. We give the circularly averaged surface brightness profiles and the photometric parameters of the 762 program galaxies, D(n) diameters, half-luminosity radii, total magnitudes, and average effective surface brightnesses. More than 80 percent of the profiles have a global S/N ratio larger than 300. The extrapolation needed to derive total magnitudes is less than 10 percent for 80 percent of the fits. More than 80 percent of the galaxies have mean effective surface brightness larger than the observed sky brightness. In 90 percent of the profiles the estimate of the contamination of the sky by the galaxy light is less than 1 percent. We derive total magnitudes and half-luminosity radii to better than 0.15 mag and 25 percent, respectively, for 90 percent of our sample. In contrast, external comparisons show that data in the literature can be strongly affected by systematic errors due to large extrapolations, small radial range, sky subtraction errors, seeing effects, and the use of a simple R exp 1/4 fit. The resulting errors can easily amount to more than 0.5 mag in the total magnitudes and 50 percent in the half-luminosity radii. Show more