Spectrum of the CH₃NC 3mm detected lines at the HCO peak (i.e., the PDR position, top spectrum) and the DCO⁺ peak (i.e., inside the cold dense core, bottom spectrum), the spectrum towards the HCO peak has been shifted vertically by 0.1 K for clarity. The panel displays the K set of lines for the given ΔJ set of lines. The frequencies corresponding to each transitions are displayed as vertical bars. The best fit model is overplotted in red. The green horizontal lines display the ± 3σ significance levels.