As Fig. 3, for MRS channels 3 and 4. The MRS channel 4 spectra is shown up to 27 μm due to uncertainties in the photometrical calibrations for λ > 27 μm. The comparison with the Spitzer IRS long low spectrum (red line, from Jarrett et al. 2011) shows excellent photometric agreement from 14.5 to 22 μm (see text for details) and illustrates how the gain in spectral resolution provided by the MRS helps to detect weak PAH features and weak lines (compared to the continuum), in particular, the high-excitation [NeV] lines.