Аннотация: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 2007 to 2020. We summarize our previously published spectroscopic and photometric results and present new observations. We
reported on the alteration in the spectral type of NGC 1566 in 2018 ( Paper I). Moreover, we focused on the exceptional postmaximum behavior after
2018 July, when all bands dropped with some fluctuations (Paper II). We ob-
served four significant re-brightenings in the post-maximum period. We have
found differences in X-ray and UV/Optical variability. The Luv/Lx ratio was
decreased during 2018-2020. New post-maximum spectra covering the period
2018 November 31 to 2019 September 23 show dramatic changes compared
to 2018 August 2, with fading of the broad lines and [Fe X] λ6374 until 2019
March (REF2). Effectively, two changing look (CL) states were observed for
this object: changing to type 1.2 and then returning to the low state as a type
1.8 Sy. We suggest that the changes are mostly due to fluctuations in the
energy generation.
Variability properties of NGC1566 are compared with our results for other CL
active galactic nuclei (AGNs).