Spectroscopic redshift histogram for galaxies within 30 arcmin of the RXC J2306.6−1319 cluster position. The peaks of this distribution are fitted with Gaussian functions (red dashed lines), obtaining z = 0.068 ± 0.002 for the low-redshift peak and z = 0.109 ± 0.003 for the high-redshift structure. The solid lines show the likelihood distribution of the redshift parameter obtained from the joint X-ray spectral fitting of the two structures shown in Fig. 1. The blue line shows the southeastern component, while the purple one the northwestern object.