Observations of AGN with MIDI

The capabilities of MIDI and the VLTI play a key role in the study of the central region of active galaxies, because the instrument (a) operates at the necessary wavelength range, namely the mid infrared, and because (b) it provides the necessary spatial resolution to analyse the circumnuclear dust distribution in these objects. The observations, however, turn out to be challenging due to the faintness of the sources, which are close to the sensitivity limit of MIDI. Nevertheless six objects have been observed successfully so far, more than originally anticipated. The faintness has implications for the data reduction, which can only be accomplished using the coherent data reduction package EWS. In spite of these challenges, MIDI has produced interesting results for the sources analysed: NGC 1068 and Circinus seem to confirm the picture of a geometrically thick dust distribution, while the nuclear MIR emission of Centaurus A appears to be mainly of non-thermal origin. The remaining objects are barely resolved and more data is needed to determine the properties of their dust emission.