Strip lines of the velocity integrated intensities of all the ¹²CO (top) and the HCN and HCO⁺ (bottom) lines we have mapped so far, at the same declination Δδ = 30′′ (PA 90°) across the ionization front of M17 SW. The ¹²CO J = 7 → 6 and J = 6 → 5 are from Pérez-Beaupuits et al. (2010), the ¹²CO J = 13 → 12 is from Pérez-Beaupuits et al. (2012), while ¹²CO J = 2 → 1 and J = 1 → 0 are from Pérez-Beaupuits et al. (2015). The rest of the lines are from this work. All maps were convolved to a 25′′ beam to match the resolution of the ¹²CO J = 11 → 10 map. The X-axis corresponds to the actual offset in RA of the maps shown in Figs. 1–3. The offset, Δα = 0′′ in RA, corresponds to the reference illuminating star SAO 161357.