| Abstract |
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 from the X-ray to the near-IR. The facilities included the telescopes of the SAI MSU, MASTER Global Robotic Net, the 2.3-m WIRO telescope, Swift, and others. We found significant variability at all wavelengths and, specifically, in the intensities and profiles of the broad Balmer lines. We measured time delays of ∼6 d (∼8 d) in the responses of the Hβ (Hα) line to continuum variations. We found the X-ray variations to correlate well with the UV and optical (with a small time delay of a few days for longer wavelengths). The K-band lagged the B band by 14 ± 4 d during the last three seasons, which is significantly shorter than the delays reported previously by the 2016 and 2017–2019 campaigns. Near-IR variability arises from two different emission regions: the outer part of the accretion disc and a more distant dust component. The HK-band variability is governed primarily by dust. The Balmer decrement of the broad-line components is inversely correlated with the UV flux. The change of the object’s type from Sy1 to Sy1.8 was recorded over a period of ∼8 yr. We interpret these changes as a combination of two factors: changes in the accretion rate and dust recovery along the line of sight. |
| Authors |
V. L. Oknyansky  , Michael S. Brotherton  , Sergey S. Tsygankov , А. В. Додин , А. М. Татарников , Pu Du , Dong-Wei Bao , М. А. Бурлак , Н. П. Иконникова , В. М. Липунов , E. Gorbovskoy , V. G. Metlov , A. A. Belinski , N. I. Shatsky , S. G. Zheltouhov , Н А Масленникова , Wang Jm , Shixiang Zhai , Fang Feng , Yunchong Fu , Hui Bai , David C. Kasper , Nazim Huseynov , Jacob N. McLane , Jaya Maithil , T. E. Zastrocky , Kurt Olson , X. Chen , Doron Chelouche , R. S. Oknyansky , D. Buckley , N. Tyurina , Alexey Kuznetsov , R. Rebolo , Bi-Xuan Zhao
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