Four vertical panels showing N₂H⁺ (J = 1–0) spectra and corresponding fitted models at four different positions from left to right as indicated by the arrow in Fig. 7b. The solid grey line are the observed spectra at each location. The red dashed line corresponds to the best fit model of the top panel spectrum, which has then been over-plotted on the bottom three panels for reference. The dashed blue lines correspond to the best fit models to the bottom three spectra. All fits have been calculated using GILDAS.