IRAM data. Panel a: a typical ¹²CO(2-1) profile near the cloud centre. Panel b: average spectrum for Δδ ≤−6 ′′ (red continuous profile) and for Δδ ≥ +2 ′′ (blue histogram). Note the sharp blue- and red edges. Panel c: profile of the quiescent emission: the average of all spectra with Δα = +27 ′′, −54 ′′ ≤ Δδ ≤ 50 ′′. All offsets are relative to the position of the YSO (2MASS coordinates, see Table 1). The dashed lines at 1.9 and 3.4 km s⁻¹ bracket both the “dip” in the CO-profile and the emission of the quiescent gas.