Name of the Speaker(s): Hagen-Thorn Vladimir A.
Title of the communication: Variable sources in AGNs
Preliminary abstract (12 lines max.): Photometric variability is one of the main manifestations of nuclear activity. Variable point sources located at the very nucleus are evidently responsible for such activity. Multicolour observations of variability allow to obtain some information on spectral energy distribution of these sources even without knowledge of their contribution to total observed fluxes. The method of analysis will be briefly discussed and some results important for establishing the nature of the sources will be given for a number of famous blazars.