CO transitions in the SiO peak (left panels) and knot (right panels) positions indicated in Fig. 2: APEX (3–2), black line; (4–3), red line; (6–5), green line and histograms (upper panels); (7–6), dark blue lines; SOFIA (11–10), pink lines and (16–15), grey lines (lower panels, overlaid on the green histograms of the 6–5 transition). The last two were multiplied by five for comparison purposes. Respective spectral resolutions are 0.33, 0.50, 0.64, 0.54, 0.90 and 0.62 km s^-1. The vertical dotted line marks the cloud velocity, −4.5 km s^-1 (Bourke et al. 1995b).