MCXC J0056.0-3732, a case in which the RXGCC position has an offset with respect to the X-ray peak due to a nearby point source. We have associated the MCXC and RXGCC clusters because both detections come from the same X-ray emission, although the RXGCC catalogue has chosen an incorrect redshift (from the nearby cluster Abell S 102) and its flux may be contaminated. The left and right panels show the RASS and XMM-Newton images, respectively. The positions of MCXC J0056.0-3732 (z = 0.163) and RXGCC 42 (z = 0.056) are marked with a light blue cross and a small red circle, respectively. The corresponding solid and dashed circles represent the size θ₅₀₀ of the clusters and their aperture radius. The magenta plus represents the position of Abell cluster Abell S 102 (z = 0.056).