89 citations · 275 across the 19 of their papers we have counts for
20 papers
In the Eye of the Storm: The Third Giant X-ray Outburst of the Extreme Changing-look AGN IC 3599
D. Grupe, S. Komossa, W. Zheng +10
We report the discovery and multiwavelength follow-up observations of a giant (factor >100) X-ray outburst of the exceptional changing-look active galactic nucleus (AGN) IC 3599. T…
Spectropolarimetry of the changing-look active galactic nucleus NGC 1566 and its potential link to supermassive black hole binaries
F. Marin, V. H. Sasse, J. Biedermann +4
The AGN NGC~1566 is known to present dramatic and regular spectral shape changes, associated with the appearance and disappearance of broad emission lines. The underlying mechanism…
Long-term multiwavelength monitoring and reverberation mapping of NGC 2617 during a changing-look event
V. L. Oknyansky, M. S. Brotherton, S. S. Tsygankov +32
We present the results of photometric and spectroscopic monitoring campaigns of the changing look AGN NGC~2617 carried out from 2016 until 2022 and covering the wavelength range fr…
Interpretation of IR variability of AGNs in the hollow bi-conical dust outflow model
V. L. Oknyansky, C. M. Gaskell
We show that, contrary to simple predictions, most AGNs show at best only a small increase of lags with increasing wavelength in the J, H, K, and L bands . We suggest that a possib…
On the possibility for measuring the Hubble constant from optical-to-NIR variability time delay in AGNs
Victor Oknyansky
The Optical-to-Near-infrared variability time delay have already been reported for a small number (about 7) of AGNs and has been firmly established only for 5 of them. The time del…
Changing looks of the nucleus of the Seyfert galaxy NGC 1566 compared with other changing-look AGNs
Victor L. Oknyansky
We present results of a long-term optical, UV and X-ray study of variability of the nearby changing-look (CL) Seyfert NGC 1566 which was observed with the Swift Observatory from 20…
Multi-Wavelength Monitoring and Reverberation Mapping of a Changing Look Event in the Seyfert Galaxy NGC 3516
V. L. Oknyansky, M. S. Brotherton, S. S. Tsygankov +26
We present the results of photometric and spectroscopic monitoring campaigns of the changing look AGN NGC 3516 carried out in 2018 to 2020 covering the wavelength range from the X-…
Changing looks of the nucleus of Seyfert galaxy NGC 3516 during 2016-2020
V. L. Oknyansky, Kh. M. Mikailov, N. A. Huseynov
The results of spectral observations of NGC 3516 with the 2-m telescope of the Shamakhy Astrophysical Observatory during 2016-2020 are presented. In the first half of 2016, the int…
The post-maximum behaviour of the changing-look Seyfert galaxy NGC 1566
V. L. Oknyansky, H. Winkler, S. S. Tsygankov +6
We present results of the long-term multi-wavelength study of optical, UV and X-ray variability of the nearby changing-look (CL) Seyfert NGC 1566 observed with the Swift Observator…
A flare in the optical spotted in the changing-look Seyfert NGC 3516
D. Ilic, V. Oknyansky, L. C. Popovic +14
We present observations from the short-term intensive optical campaign (from Sep2019 to Jan2020) of the changing-look Seyfert NGC 3516. This active galactic nucleus is known to hav…
Variability and the size-luminosity relation of the intermediate mass AGN in NGC 4395
Hojin Cho, Jong-Hak Woo, Edmund Hodges-Kluck +31
We present the variability study of the lowest-luminosity Seyfert 1 galaxy NGC 4395 based on the photometric monitoring campaigns in 2017 and 2018. Using 22 ground-based and space…
The Relative Wavelength Independence of IR Time Lags in NGC4151 During the Years 2010-2015
V. L. Oknyansky, V. I. Shenavrin, N. V. Metlova +1
We present results of a study of the correlation between the infrared (JHKL) and optical(B) fluxes of the nucleus of the Seyfert galaxy NGC 4151 for the years 2010 - 2015 using our…
Supernova 2018aoq and a distance to Seyfert galaxy NGC 4151
D. Yu. Tsvetkov, P. V. Baklanov, M. Sh. Potashov +9
We present optical photometric observations of SN 2018aoq from 2 to 100 days after explosion, and 7 spectra at epochs from 11 to 71 days. The light curves and spectra are typical f…
New changing look case in NGC 1566
V. L. Oknyansky, H. Winkler, S. S. Tsygankov +5
We present a study of optical, UV and X-ray light curves of the nearby changing look active galactic nucleus in the galaxy NGC 1566 obtained with the Neil Gehrels Swift Observatory…
Changing-look Narrow-Line Seyfert 1s?
Victor L. Oknyansky, Konstantin L. Malanchev, C. Martin Gaskell
Two major challenges to unification schemes for active galactic nuclei (AGN) are the existence of Narrow-Line Seyfert 1s (NLS1s) and the existence of changing-look (CL) AGNs. AGNs…
Multi-wavelenth monitoring of the changing-look AGN NGC 2617 during state changes
V. L. Oknyansky, C. M. Gaskell, N. A. Huseynov +18
Optical and near-infrared photometry, optical spectroscopy, and soft X-ray and UV monitoring of the changing-look active galactic nucleus NGC 2617 show that it continues to have th…
The curtain remains open: NGC 2617 continues in a high state
V. L. Oknyansky, C. M. Gaskell, N. A. Huseynov +17
Optical and near-infrared photometry, optical spectroscopy, and soft X-ray and UV monitoring of the changing look active galactic nucleus NGC 2617 show that it continues to have th…
The relative wavelength independence of IR lags in active galactic nuclei: implications for the distribution of the hot dust
V. L. Oknyansky, C. M. Gaskell, E. V. Shimanovskaya
We show that, contrary to simple predictions, most AGNs show at best only a small increase of lags in the J, H, K, and L bands with increasing wavelength. We suggest that a possibl…
New Estimates of Time Delays in the Gravitationally Lensed System PG1115+080
E. Shimanovskaya, V. Oknyansky, B. Artamonov
We analyze all publicly available long-term optical observations of the gravitationally lensed quasar PG1115+080 for the purpose of estimating time delays between its four componen…
Reverberation measurement of the inner radius of the dust torus in NGC 4151 during 2008-2013
V. L. Oknyansky, N. V. Metlova, O. G. Taranova +4
We investigate the correlation between infrared (JHKL) and optical (B) fluxes of the variable nucleus of the Seyfert galaxy NGC 4151 using partially published data for the last 6 y…