Paper detail

Surface photometry of WINGS galaxies with GASPHOT

Aims. We present the B-, V- and K-band surface photometry catalogs obtained running the automatic software GASPHOT on galaxies from the WINGS cluster survey having isophotal area larger than 200 pixels. The catalogs can be downloaded at the Centre de Donnees Astronomiques de Strasbourg (CDS). Methods. We outline the GASPHOT performances and compare our surface photometry with that obtained by SExtractor, GALFIT and GIM2D. This analysis is aimed at providing statistical information about the accuracy generally achieved by the softwares for automatic surface photometry of galaxies. Results. For each galaxy and for each photometric band the GASPHOT catalogs provide the parameters of the Sersic law best-fitting the luminosity profiles. They are: the sky coordinates of the galaxy center (R:A:; DEC:), the total magnitude (m), the semi-major axis of the effective isophote (Re), the Sersic index (n), the axis ratio (b=a) and a flag parameter (QFLAG) giving a global indication of the fit quality. The WINGS-GASPHOT database includes 41,463 galaxies in the B-band, 42,275 in the V-band, and 71,687 in the K-band. We find that the bright early-type galaxies have larger Sersic indices and effective radii, as well as redder colors in their center. In general the effective radii increase systematically from the K- to the V- and B-band. Conclusions. The GASPHOT photometry turns out to be in fairly good agreement with the surface photometry obtained by GALFIT and GIM2D, as well as with the aperture photometry provided by SExtractor. The main advantages of GASPHOT with respect to other tools are: (i) the automatic finding of the local PSF; (ii) the short CPU time of execution; (iii) the remarkable stability against the choice of the initial guess parameters. All these characteristics make GASPHOT an ideal tool for blind surface photometry of large galaxy samples in wide-field CCD mosaics.