Abstract

We present deep wide-field (16.4x16.4 arcmin(2)) Washington CT(1) CCD surface photometry of the giant elliptical galaxy NGC 4472, the brightest member of the Virgo cluster. Our data cover a wider and deeper field than any previous CCD photometry. A single King model does not give a good fit to the surface brightness profiles of NGC 4472, but they can be fitted approximately using two King models: with the separate models representing the inner and outer regions. Surface brightness profiles for the outer region can also be fitted approximately by a de Vaucouleurs law. There is clearly a negative colour gradient within 3 arcmin of NGC 4472, in the sense that the colour gets bluer with increasing radius. The slope of the colour gradient for this region is derived to be Delta mu(C-T(1))=-0.08 mag arcsec(-2) for Delta log r=1, which corresponds to a metallicity gradient of Delta[Fe/H]=-0.2 dex. However, the surface colour becomes gradually redder with increasing radius beyond 3 arcmin. A comparison of the structural parameters of NGC 4472 in C and T(1) images has shown that there is little difference in the shapes of ellipses observed using isochromes or isophotes. In addition, photometric and structural parameters of NGC 4472 have been determined.