SCAT Classification of ASASSN-22cy as a Likely Optical Changing-Look AGN in NGC3822
ATel #15280; J. T. Hinkle, T. de Jaeger, B. J. Shappee, C. Ashall, D. Desai, A. Do, M. E. Huber, A. V. Payne, M. A. Tucker (IfA, Hawai'i), K. Z. Stanek, J. M. M. Neustadt (Ohio State)
on 16 Mar 2022; 08:14 UT
Credential Certification: Jason Hinkle (jhinkle6@hawaii.edu)
Subjects: Optical, AGN, Black Hole, Transient
Referred to by ATel #: 15350
ASASSN-22cy (AT2022eiu) was discovered by the All-Sky Automated Survey for Supernovae (ASAS-SN; Shappee et al. 2014, Kochanek et al. 2017) on UT 2022-03-04.14 at g = 16.7 mag. The position of the transient was consistent with the nucleus of the host galaxy (NGC 3822), which has a redshift of z = 0.020894 from H I spectra on the NASA/IPAC Extragalactic Database (NED).
A classification spectrum was obtained with the Supernova Integral Field Spectrograph (SNIFS) on the University of Hawaii 88-inch telescope on 2022-03-11 as part of the Spectral Classification of Astronomical Transients (SCAT) program (ATel #11444). The spectrum shows a weak blue continuum with broad (~5000 km/s) Balmer and He I lines at the host galaxy redshift, consistent with the spectrum of a Seyfert 1. An archival spectrum of NGC3822 presented in Moran et al. (1996) shows only broad H-alpha emission without accompanying broad H-beta, consistent with a Seyfert 1.9 classification.
We also obtained archival light curves of NGC3822 from the Catalina Real-time Transient Survey (CRTS; Drake et al. 2009), Asteroid Terrestrial-impact Last Alert System (ATLAS; Tonry et al. 2018), and ASAS-SN to search for previous activity. Besides the recent flare associated with the transient ASASSN-22cy, there is no strong variability observed for NGC3822, consistent with the earlier Seyfert 1.9 classification.
Based on the recent flux increase and the appearance of broad emission lines, we classify ASASSN-22cy as a likely optical changing-look AGN in NGC3822. We are currently obtaining follow-up UV/optical and X-ray observations with Swift in addition to optical spectroscopy. We encourage further follow-up of this source, particularly high S/N spectroscopy.
