SIMBAD references

We investigated the optical properties of 7 clusters of galaxies observed in three colors over the range of absolute magnitudes -24≤M≤-12. Our aim is to estimate the Luminosity Function and the total cluster luminosity of our sample in order to have information about the formation and the evolution of galaxies in clusters. In this paper, we present the main points of our analysis and give the formal parameters obtained by fitting the data using the maximum likelihood algorithm. We find consistency between our results and other works in literature confirming the bimodal nature of the luminosity function of cluster galaxies. More important, we find that the relation L_opt/L_X versus L_X is color dependent: Low X ray Luminosity clusters have a bluer galaxy population.