PUBLICATIONS OF THE ASTRONOMICAL OBSERVATORY OF BELGRADE104, Page 11-18, https://doi.org/10.69646/aob104p011
PROCEEDINGS of the XX Serbian Astronomical Conference, Belgrade, October 16 - 20, 2023, Edited by Jelena Petrović, Dušan Marčeta and Ana Lalović
Published by: Astronomical Observatory, Volgina 7, 11060 Belgrade 38, Serbia

Abstract. All active galactic nuclei (Seyfert 1 galaxies, quasars) are variable in the con- tinuum flux. Furthermore, their broad emission lines vary as well on time scales of weeks to years. First, we will present the results of variability campaigns on two prototype AGN. Then we will show what we can learn from the variability about the geometry and kinemat- ics in the innermost regions that are surrounding the central supermassive black holes. The second part is dedicated to galaxies that show extreme variations in their spectral profiles - the so-called changing look AGN.