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Optical identification of two INTEGRAL sources

ATel #1363; I. Bikmaev (KSU, AST), M. Revnivtsev (IKI, MPA), R. Burenin (IKI), S. Sazonov (IKI, MPA), R. Sunyaev (MPA, IKI), M. Pavlinsky (IKI), A. Galeev (KSU, AST), N. Sakhibullin (KSU, AST)
on 21 Jan 2008; 10:59 UT
Credential Certification: M.Revnivtsev (mikej@hea.iki.rssi.ru)

Subjects: Optical, X-ray, AGN

We report optical spectroscopic identification of two INTEGRAL sources, detected in the INTEGRAL all-sky survey (published version Krivonos et al. 2007, A&A, 475, 775, current version of the catalog http://hea.iki.rssi.ru/rsdc/catalog/index.php ). The original astrometric position of one of the sources was refined using SWIFT/XRT data. Optical data were obtained with the Russian-Turkish 1.5-m telescope (RTT-150, Bakirlitepe, TUBITAK National Observatory, Turkey), using TUG Faint Object Spectrograph and Camera (TFOSC).

IGR J23206+6431 --- The hard X-ray source was detected on images of the Galactic plane obtained by INTEGRAL/IBIS after collecting exposure time additional to that used in the paper of Krivonos et al. 2007. The time average flux of the source in the 17-60 keV energy band is 0.6+/0.1 mCrab. The source was observed by SWIFT/XRT and is associated with 2MASX J23203662+6430452, preliminary classified as a galaxy by 2MASS catalog.

RTT150 images obtained in the Rc filter reveal the presence of an extended object at the position of the 2MASX source (Rc ~ 19 mag). The optical spectrum is heavily reddened due to the high Galactic absorption (E(B-V) = 1.89) in the direction to the source ( LII = 113.4, BII = 3.3 degrees) and shows redshifted and broad H-alpha line (FWHM = 120 A) and narrow [ O III, 5007 ] emission line. Using the [ O III ] line we measured the redshift z=0.07173 (consistent with the redshift measured using the broad H-alpha line, z = 0.07167). The estimated de-reddened optical luminosity of the source is ~ 10^{44} erg/sec. Taking into account the broad H-alpha line and high optical luminosity we classify this source as Seyfert 1 AGN.

We determined the optical astrometric position by using RTT150 images relative to USNO-B1.0: R.A.(2000.0) = 23 20 36.576, Dec. = +64 30 45.15

Note the presence of a point like source of comparable optical brightness 7 arcsec east of AGN, at R.A.(2000.0) = 23 20 37.092, Dec.(2000.0) = 64 30 45.048, which may overlap with the AGN at photographic images of optical surveys.

IGR J02524-0829 --- The source is associated with the nearby edge-on spiral galaxy MCG-02-08-014. The optical spectrum of the nucleus region of this galaxy shows redshifted narrow H_alpha and [NII],6583 and [ S II ] lines in emission. From the intensity ratio lg([NII],6583/H_alpha) = +0.36, we conclude that this source most probably is a Seyfert 2 AGN (Veilleux & Osterbrock, 1987). This is also confirmed using the spectrum from 6dFGS DDR2 (Jones et al., 2004, MNRAS, 355, 747), who measured the redshift z=0.016721 for this object.

We would like to thank the Swift Team and in particular N.Gehrels for making observation of IGR J23206+6431 possible