Changing looks of the nucleus of the Seyfert galaxy NGC 1566 compared
  with other changing-look AGNs
  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 (REF1). Moreover, we
focused on the exceptional postmaximum behavior after 2018 July, when all bands
dropped with some fluctuations (REF2). We observed four significant
re-brightenings in the post-maximum period. We have found differences in X-ray
and UV/Optical variability. The L_uv/L_x-ray 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] 6374 until 2019 March (REF2). Effectively, two 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
AGNs.
