Observed spectra of the species identified in the frequency coverage of the N₂H⁺−N₂D⁺ data (black histograms). The transitions are labelled in the top-left corner of each panel. The red histograms show the spectral fit performed with CLASS, which is a Gaussian fit for all transitions except for the ND₃ and CN ones, for which we fit the hyperfine structure using the HFS routine. The vertical dotted line in each panel shows the source V_lsr = 5.65 km s⁻¹, corresponding to the weighted average measured in the N₂H⁺ and N₂D⁺ lines.