Integrated intensity maps of H₂CO 3_0,3−2_0,2 in velocity bins of 30 km s^-1. Labels and contour steps as in Fig. 12. Note that the observed emission toward the north and east in the −120 and −90 km s^-1 maps correspond to the high-velocity emission of HC₃N 24−23 (218.324 GHz) detected at the edge of the observed band (Sect. 3).