Left: XMM-Newton EPIC(PN, MOS1, MOS2) image in [0.2–12] keV of ObsID=0142610101 for Abell 0412 (C1) and the other two clusters (C2 and C3). The blue circle indicates the BCG position, which is located to the south-west of C1 position. Middle: deep S82 image in the r band corresponding to the X-ray image. The overplotted contours (yellow) are X-ray surface brightness contours in [0.2–12] keV. Right: density map of the galaxies with photometric redshifts within z_CLG ± 0.03(1 + z_CLG) of the cluster redshift (see text). The contours start at 4σ and increase by 2σ. In the three images, the cyan circles have one arcmin radii and are centred on the X-ray emission peaks of the three (C1, C2, C3) X-ray sources. The sizes of all images are 25 × 25 arcmin² (~3 × 3 Mpc²).