Aims. We have calculated variability Doppler boosting factors, Lorentz factors, and viewing
angles for a large sample of sources by using total flux density observations at 22 and 37 …

We have conducted a multiwavelength survey of 42 radio loud narrow-1ine Seyfert 1
galaxies (RLNLS1s), selected by searching among all the known sources of this type and …

Aims. Since the CGRO operation in 1991–2000, one of the primary unresolved questions
about the blazar γ-ray emission has been its possible correlation with the low-energy (in …

Aims. We have studied the flare characteristics of 55 AGN at 8 different frequency bands
between 4.8 and 230 GHz. Our extensive database enables us to study the various …

Context. The blazar sequence is a scenario in which the bolometric luminosity of the blazar
governs the appearance of its spectral energy distribution. The most prominent result is the …

Aims. We present a study of variability time scales in a large sample of Active Galactic Nuclei
at several frequencies between 4.8 and 230 GHz. We investigate the differences of various …

IceCube alert events are neutrinos with a moderate-to-high probability of having
astrophysical origin. In this study, we analyze 11 yr of IceCube data and investigate 122 alert …

We report multiwavelength observations of the gravitationally lensed blazar QSO B0218+
357 in 2016–2020. Optical, X-ray, and GeV flares were detected. The contemporaneous …

Observations performed at Metsähovi Radio Observatory at 37 GHz are presented for a
sample of 78 radio-loud and radio-quiet narrow-line Seyfert 1 (NLS1) galaxies, together with …

Blazars are a class of active galactic nuclei that host relativistic jets oriented close to the
observer's line of sight. Blazars have very complex variability properties. Flares, namely flux …