Deep photometry and integral magnitudes of 8 nearby galaxies

Abstract

We estimated integral magnitudes of galaxies trying to include the contribution of the brightest part of their halos. We performed surface photometry based on (i) concentric elliptical rims, corresponding to the peripheral ellipticity of the image, (ii) median estimation of the mean value of the rim pixels, (iii) apparent radial brightness profiles, corresponding to the rim medians, and (iv) magnitude curves of growth, derived by numerical integrations of the apparent rim profiles, without preliminary background estimation and removal. Furthermore, we used the magnitude curves of growth to determine the integral magnitudes (limited by size and deepness of our frames) and compared them with the total magnitudes in the data base HyperLeda. Also, we used the rim-profiles to estimate the background level far enough from the galaxy center and we build (here—only for trial) the intrinsic radial profiles (with background removal). We apply this photometry on 8 nearby galaxies, observed with CCD in the system BVRC IC by the 50 cm Schmidt telescope of the Rozhen NAO in 2003–2004. We build radial profiles which occur to be as average 1.8 times (1.2–2.5 times) larger than in data base NED and of integral brightness that occurs to be about 1.4 times (1.2–1.7 times) higher than in data base HyperLeda. The relative brightness additions, found here, correlate with the color index and anti-correlate with the luminosity of the galaxy.