Identical channel maps to Fig. 4, slightly more zoomed in. The white cross on the position of the centre of the SiO emission void to highlight the coincidence between its position and the features in the CO emission. The yellow arc to the north in the red-shifted channels highlights the emission that is associated with the launching of the wake-spiral. The red arc to the south in the blue-shifted challes highlights the emission associated with the reflex-spiral.