a) ISO-SWS spectrum in the N-band range. The PAH features at 8.6, 11.3, 12.0, and 12.7 μm are indicated, the dashed line represents the continuum. b) Spatial extent along the slit north-south direction of VISIR. The dashed line indicates the width of the spatially unresolved continuum, which increases with wavelength. c) Relative spatial position with respect to the continuum along the slit direction of VISIR. The PAH emission region is extended on a scale of several 100 s of AU and its photocenter is located towards the south of the continuum emission region.