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 postmaximum period. We have found differences in X-ray and UV/Optical variability. The Luv>/Lx ratio was decreased during 2018-2020. New postmaximum spectra covering the period November 31, 2018 to September 23, 2019 show dramatic changes compared to August 2, 2018, 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.
- Pub Date:
- January 2022
- galaxies: active;
- galaxies: Seyfert;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Astrophysics of Galaxies
- 7 pages, 2 figures, accepted by AstronNachr. arXiv admin note: substantial text overlap with arXiv:2006.00001