Spectra from location N158 indicated by the crosses in Fig. 1 averaged in apertures drawn around the location with a 15″ diameter. The measured spectra are shown by the connected black stars. The dashed black line shows the fit signal. For the [O III] spectra the fit baseline is additionally shown as a red line. Details of the line fit can be found in section 2.1.3. Top: [C II], Bottom: [O III].