First moment maps (intensity-weighted peak velocities) of [CI] (left panel) and ¹³CO(3–2) (right panel)over a velocity range of [71,86] km s⁻¹. The contours show the 875 μm emission from the ATLASGAL survey (Schuller et al. 2009; contour levels start at the 4σ level of 200 mJy beam⁻¹ and continuein 8σ steps up to 1.8 Jy beam⁻¹). The white lines show the direction (north to south) of the pv-diagrams in Fig. 9. The stars in the left panel show the positions of the spectra presented in Fig. 8. A scale bar is shown in the left panel. The black rectangle in the right panel outlines the region with the velocity jump.