Results of LTE-modeling of spectra for selected transitions of CH₃CN, H₂CO, HC₃N and SO at S1. The black histograms show the observed spectra and the red continuous lines correspond to the spectra predicted by the best fit model. All transitions of a particular species have been fitted simultaneously using CASSIS as is mentioned in the text. The reduced χ² values for the model fits are 1.68 (CH₃CN), 0.95 (H₂CO), 0.95 (HC₃N), 0.87 (SO), 1.02 (N₂H⁺).