Top panel: position-velocity (PV) diagram of 4C 52.37 along a cut aligned with the largest extent of the central absorption feature. The solid, horizontal line corresponds to the systemic velocity. The dashed, vertical lines mark the size of the synthesized beam. Contour lines correspond to 3 (grey, solid), −2 (black, dashed), −3, and −5 (black, solid) times the noise level in the cube. Middle panel: contour lines show the continuum radio emission as in Fig. 1 with the color map corresponding to . The dashed lines represent the cuts for the PV diagram. Bottom panel: same as top panel, but a cut along the position angle of W1 and E1. The top and bottom panels are centred on E1.