Channel maps around the Mg IIλ2796 emission. Each map corresponds to one MUSE subcube slice (1.25 Å or 58 km s⁻¹ at the redshift of the group). The velocity window relative to the systemic redshift of galaxy A is indicated on each panel. Contours are the same as in Fig. 3a. The eight central slices (from −177 to +286 km s⁻¹) are summed to create the optimized λ2796 Mg II NB image shown in Fig. 3a (see Sect. 4.1).