Images of G071.63+29.78. Top: LOFAR at 144 MHz and uGMRT at 400 MHz radio images (units are Jy beam⁻¹). The resolution and noise are reported at the top of each panel. The contour levels are [ ± 3,  6,  12,  …] × σ. Bottom left: Pan-STARRS optical (composite i, r, g filter) image. The orange contours are from the radio images in the top panels. The green circles and cyan lines indicate optical sources and regions discussed in the text. Bottom centre: 144–400 MHz spectral index map (the error map is shown in Fig. A.1). The contour levels are [ ± 3,  6,  12,  …] × σ from the 144 MHz image. Bottom right: X-ray image of the cluster. The green contours are from the LOFAR image. The red and black crosses indicate the Planck centre and X-ray peak, respectively.