Separate A- and B-array spectra towards the central beam. Spectra have been Gaussian smoothed (over two channels). We show the spectra for the A- and B-array separately to emphasize that identified features appear in both separate datasets. The central spectrum for the combined A+B dataset is shown in Fig. 6. Left: B-array spectrum of HCN J = 3−2, HCO⁺J = 3−2, HCN J = 3−2ν₂ = 1, and a tentative detection of HOC⁺J = 3−2. Right: a-array spectrum of the same lines. The green velocity scale is for HCO⁺.