A4 Refereed article in a conference publication
Discovery of new changing look in NGC 1566
Authors: Oknyansky Victor L., Tsygankov Sergey S., Lipunov Vladimir M., Gorbovskoy Evgeny S., Tyurina Nataly V.
Editors: Mirjana Pović, Paola Marziani, Josefa Masegosa, Hagai Netzer, Seblu H. Negu, Solomon B. Tessema
Conference name: Symposium of the International Astronomical Union
Publisher: Cambridge University Press
Publication year: 2021
Journal: Proceedings of the International Astronomical Union
Book title : Nuclear Activity in Galaxies Across Cosmic Time
Journal name in source: Proceedings of the International Astronomical Union
Series title: Proceedings of the International Astronomical Union
Number in series: S356
Volume: 15
First page : 127
Last page: 131
ISSN: 1743-9213
eISSN: 1743-9221
DOI: https://doi.org/10.1017/S1743921320002720
We present continuation of the multi-wavelength (from X-ray to optical) monitoring of the nearby changing look (CL) active galactic nucleus in the galaxy NGC 1566 performed with the Neil Gehrels Swift Observatory,the MASTER Global Robotic Network over the period 2007-2019. We also present continuation of optical spectroscopy using the South African Astronomical Observatory 1.9-m telescope between Aug. 2018 and Mar. 2019. We investigate remarkable re-brightenings in of the light curve following the decline from the bright phase observed at Dec. 2018 and at the end of May 2019. For the last optical spectra (31 Nov. 2018-28 Mar. 2019) we see dramatic changes compared to 2 Aug. 2018, accompanied by the fading of broad emission lines and high-ionization [FeX]6374Å line. Effectively, one more CL was observed for this object: changing from Sy1.2 to the low state as Sy 1.8-Sy1.9 type. Some possible explanations of the observed CL are discussed.
