Nearby clusters of galaxies. I.

This paper describes the data, derived from automated scans of photographic plates. Different methods for the evaluation of cluster center, ellipticity and orientation are compared and errors are estimated by Monte Carlo simulations.

We present the results of the analysis of 1256 galaxies brighter than m_3_+3 in eight Abell clusters. We find that different methods give consistent estimates of ellipticity and orientation, provided the radial dependence of these quantities is taken into account. We also find that central densities are consistent with isothermal fits if the center is selected as the baricenter of the cluster.