Rotation diagrames and synthetic spectrum fits of CH₃CN, HNCO, and H₂CO in MM1 (or MM2) and IRS1-mmS. Panels 1–2 present the CH₃CN spectra towards MM1 and IRS1-mmS in black, fitting with optically thin assumption in dashed purple, and fitting with opacity correction in filled red. Panels 3–5 show the rotation diagrams of CH₃CN derived for MM1, MM2, and IRS1-mmS, with black dots and fits corresponding to the optically thin assumption, whereas red dots and fits include correction for opacity. Panels 6–7 present the HNCO (assumed optically thin) synthetic spectrum fits towards MM2 and IRS1-mmS, with blended lines marked (fit in red). Panels 8–10 show the rotation diagrams of HNCO (assumed optically thin). Panel 11 presents the H₂CO synthetic spectrum fits towards MM1. Panels 12 shows the data points of H₂CO lines in MM1, which cannot be fitted in the rotation diagram. The estimated T_rot and molecular column density from each rotation diagram is indicated in each panel. Errors are derived from scatter in the data points.