Zwcl0634.1+4750 NVSS map; the contour levels are 0.66 × (−1,1,2,4,6,8,10,16,32,64) mJy b^-1. The 1σ level is 0.22 mJy b^-1. In both panels the region where we extracted the flux densities are shown (solid circles). The central region has a diameter of 1 Mpc and is centred on the centroid of the X-ray emission; the other three areas are the control fields. With the task BLANK we masked the discrete sources in the central region and the one that falls in the lower control field (left panel).