A1550 seen in 144 MHz emission (red) as detected by LOFAR overlaid on the PanSTARSS optical (RGB filters) image. The radio image has a resolution of 13″ × 8″, and the beam is shown on the bottom right. The most prominent structures that are discussed in the text are labelled. Compact sources are subtracted to enhance diffuse emission as described in Sect. 2.1. The yellow cross marks the cluster X-ray centre, defined as the peak of the emission and estimated from the Chandra image presented in Sect. 2.5.