Publication of Astronomical Observatory of Belgrade, Vol. 105, 2024, Page 38, https://doi.org/10.69646/14sbac34a
BOOK OF ABSTRACTS: XIV Serbian-Bulgarian Astronomical Conference, 23 - 27 September, 2024, Vrnjačka Banja, Serbia. Editors: Milan S. Dimitrijević, Evgeni Semkov, Zoran Simić, Goran Damljanović, Momchil Dechev

Blazars form a subclass of active galactic nuclei (AGN) which eject relativistic jets along the observer’s line of sight. Their flux is highly variable in the whole electromagnetic spectrum, and show variability on diverse time-scales. Variability time-scales can be divided into three classes: intra-night variability (from a few minutes to a less than a day), short-term variability (from a few days to a few months), and long-term variability (from a few months to several years). Source 1722+119 is BL Lacertae. BL Lacertae are blazars which are characterized by rapid and large-amplitude flux variability. The observations were performed from July 2013 using telescopes located at the Astronomical station Vidojevica of Astronomical Observatory of Belgrade, Serbia. During more than ten years of flux monitoring of source 1722+119 amplitude brightness change by about 2 magnitudes in V and R bands. For a few nights we monitored this source more than 3 hours per night, and results will be presented here.