Middle panel: line integrated ¹²CO 3→2 emission in K kms^-1 on a main beam temperature scale (between 72 and 84 km s^-1) of G28.37+0.07. The dust column density from Herschel is overlaid as black contours (levels 4,5,7 × 10²² cm^-2). The dashed lines outline the area displayed in Fig. 9, and the numbering from 1 to 6 indicates the position of submm-continuum sources seen with ATLASGAL and subsequently observed in N₂H⁺ (Tackenberg et al. 2014). The ¹²CO 3→2 (black) and ¹³CO 1→0 (red) spectra at these positions are displayed in the panels around. Additionally, we show spectra from two positions (indicated by arrows) off the sources but still within the molecular cloud. The blue-dashed line denotes the centre velocity of the N₂H⁺ line.