The investigations of Active Galactic Nuclei (AGNs), and especially blazars,
represent an important part of scientific analyses of the High Energy Astrophysics
Study of selected extragalactic sources - blazars - including a study and
improvement of periods, fitting the profiles of their outbursts, and study of the
colour indices. This considers a rather new research field, reflecting the
recommendations of the international evaluation commission of the Astronomical
Institute in the year 1995 (extension of the research in the field of extragalactic
astrophysics), in which new valuable results are being obtained at present.
This study makes use of the data from the satellite INTEGRAL and from the
ground-based telescopes, including the robotic ones. In this regard, also analyses
of the correlations of various types of extragalactic objects (supernovae,
gamma-ray bursts, blazars, AGN) were conducted.