SDSS DR7 photometric redshift z_p (Artificial Neural Network estimates, Oyaizu et al. 2008) versus spectroscopic redshift z for the IR-emitting galaxies with available z and z_p in the supercluster field (471 galaxies in the displayed z and z_p ranges). The solid pink line is the identity relation z = z_p. The dash-dotted red lines indicate the chosen z_p range for membership selection (see text and Fig. 3).