[ Previous | Next | ADS ]

Optical identification of the INTEGRAL source IGR J21565+5948 as Sy1 AGN

ATel #3072; I. Bikmaev, E. Irtuganov, N. Sakhibullin (Kazan Federal University, Academy of Sciences of Tatarstan, Kazan, Russia), R. Burenin, S. Sazonov, M. Pavlinsky (Space Research Institute of the Russian Academy of Sciences, Moscow, Russia), R. Sunyaev (Space Research Institute of the Russian Academy of Sciences, Moscow, Russia, and MPA, Garching, Germany)
on 8 Dec 2010; 18:18 UT
Credential Certification: Ilfan Bikmaev (Ilfan.Bikmaev@ksu.ru)

Subjects: Optical

We report on optical spectroscopic observations of two X-ray sources detected by Swift/XRT and labeled as Sources #1 and #2 in Landi et al., ATEL#3065, located in the INTEGRAL/IBIS error circle of the hard X-ray source IGR J21565+5948.
The observations were performed on 2010 December 3,6,7 with the TFOSC instrument installed on the 1.5-m Russian-Turkish telescope (RTT-150, TUBITAK National Observatory, Antalya, Turkey). Spectral range is 3600 - 9000 Angstrom, spectral resolution is 14 Angstrom.
The spectrum of Source #1 shows an early A-type star's lines without any emission components seen at the given spectral resolution.
There are two objects with R ~ 16 mag (2MASS J21560446+5955586) and R ~ 19 mag (2MASS J21560418+5956045) within the 4 arcsec error box of the XRT coordinates of Source#2 presented in Landi et al, ATEL#3065.
The optical spectrum of the R ~ 16 mag ( 2MASS J21560446+5955586) object does not show any emission lines and exhibits a late type star's lines.
The optical spectrum of the fainter source with R ~ 19 mag, located ~ 6 arcsec North-West of the object with R ~ 16 mag, shows broad (FWHM ~ 4500 km/s) H-alpha and H-beta emission lines at redshift z = 0.208 +/- 0.001, and also a weak and narrow [O III] 5007 Angstrom emission line at the same redshift.
From these features we identify 2MASS J21560418+5956045 (coincided also with USNO-B1.0 object 1499-0325257 at coordinates R.A. (2000.0) = 21m56m04.202s, Dec. (2000.0) = +59o56'04.46") as the optical counterpart of IGR J21565+5948 and classify it as a Seyfert 1 AGN.
Note the relatively high Galactic absorption in the direction of IGR J21565+5948, corresponding to E(B-V) ~ 1.5 mag and ~ 3.5 mag absorption in the R-band. This means that the newly identified AGN has a non-absorbed R value of ~ 15.5 mag, which is within the range of optical magnitudes of the other nearby AGNs detected by INTEGRAL.
The finding chart for the optical counterpart IGR J21565+5948 and its optical spectrum can be found at the following adress:
http://hea.iki.rssi.ru/~rodion/integraloptid/images/IGR21565p5948RTT.JPG
http://hea.iki.rssi.ru/~rodion/integraloptid/images/IGR21565p5948SpecRTT.JPG