INFRARED SPECTROPHOTOMETRY OF NGC-7023 WITH ISOCAM

We present spectrophotometric observations of the reflection nebula NG C 7023 obtained with the ISOCAM Circular Variable Filter (CVF) in the spectral range 5.15 to 16.5 mu m. Maps in the 16 mu m continuum emissi on and in the Unidentified Infrared Bands (UIBs) have been obtained. T he continuum emission peaks at the dense interface between the surroun ding molecular cloud and the inner photodissociated region. The whole spectrum (UIBs and continuum) becomes systematically harder closer to the exciting star. Our observations show that it is entirely due to th e same category of carriers, probably PAHs heated transiently by singl e photons, and that the systematic spectral changes inside NGC7023 are due to changes in the size distribution or/and ionization degree of t hese particles.