Zoomed RGB image of the central area of the high-z cluster (z_spec = 0.816) associated with PSZ2 G126.57+51.61. We mark spectroscopically confirmed cluster members with yellow circles. The small top panel shows the WFC/INT i′-band image, in which white contours correspond to the 3 and 6 × 10⁻⁶ levels of the Compton y-map in this area. The red circle indicates the nominal PSZ2 position. The blue square shows the size of the area that is presented in the main RGB image.