a) Brightness ratio map derived from the SW continuum averaged over the range of 88–131 cm^-1 that is divided by the LW continuum over 66–87 cm^-1. The dashed squares indicate the aperture regions used to obtain the spectra shown in Figs. 2c and d. b) [OIII] 88 μm line intensity map overlaid on the contours of the [NII] 122 μm line intensity. The contour levels are linearly scaled from 4 × 10^-7 to 1.5 × 10^-6 W m^-2 sr^-1.