PUBLICATIONS OF THE ASTRONOMICAL OBSERVATORY OF BELGRADE104, Page 189-194, https://doi.org/10.69646/aob104p189
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. In 2011, two years before the launch of the Gaia satellite, 47 objects for the link between the future Gaia Celestial Reference Frame and International Celestial Reference Frame were proposed. We have been actively observing these 47 objects at the Astronomical Station Vidojevica since 2013. These objects are Active Galactic Nuclei and the monitoring of their brightness is important in order to investigate the physical processes which can affect their astrometric precision. The observations were performed mostly in V and R bands, and occasionally in B and I bands. Here, we present the photometry results, analysis of brightness, and V − R colour using 10 years of observations of the object 1722+119 (the most variable source in our list of objects).