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IGR J17453-2853 = Granat 1741.9-2853?

ATel #1008; E. Kuulkers (ESA/ESAC, Spain), S. Shaw (Southampton, UK), J. Chenevez, S. Brandt (DNSC, Denmark), A. Domingo (LAEFF/INTA, Spain), P. Kretschmar (ESA/ESAC, Spain), C. Markwardt (GSFC, USA), N. Mowlavi (ISDC, Switzerland), A. Paizis (INAF-IASF, Italy), D. Risquez (LAEFF/INTA, Spain), C. Sanchez-Fernandez (ESA/ESAC, Spain), R. Wijnands (UvA, The Netherlands)
on 22 Feb 2007; 08:43 UT
Credential Certification: Erik Kuulkers (ekuulker@rssd.esa.int)

Subjects: Binary, Neutron Star, Transient, Variables

Referred to by ATel #: 1013, 1025

The position of the recently found source IGR J17453-2853 as derived by INTEGRAL IBIS/ISGRI (see ATel #1005) is about 4 arcmin from that of Granat 1741.9-2853 (see ATel #1006; Muno et al. 2003, ApJ 598, 474). Formally, given the statistical 90% error regions of both sources (IGR J17453-2853: about 2 arcmin; Granat 1741.9-2853: about 1 arcsec), they can be regarded as two different sources.

However, Granat 1741.9-2853 was found to be the only X-ray transient active in the near vicinity of IGR J17453-2853 by the Swift/XRT, about a day after the INTEGRAL observations (ATel #1006). Moreover, combining our Galactic bulge monitoring observations obtained on UT 2007, February 15 18:35-22:17, February 17 14:52-18:34, and February 20 00:51-04:32, with JEM-X we find a source at RA, Dec (degrees, J2000.0) = 266.265, -28.92, with a positional error of about 2 arcmin. This is consistent with the X-ray emission being also due to Granat 1741.9-2853. It was detected at the 10 sigma level with an average JEM-X 3-10 keV flux of 7.5+/-1 mCrab; it was just at the detection limit in the JEM-X 10-25 keV band (about 5 mCrab).

In addition, the quoted Swift/XRT 2-10 keV flux and X-ray spectrum of Granat 1741.9-2853 (ATel #1006) are consistent with the quoted 20-60 keV IBIS/ISGRI flux of IGR J17453-2853 and its inferred high absorption column density, a day earlier (ATel #1005). Note that in April 2005 both sources were also reported to be active in the same time period with similar fluxes (Kuulkers et al. 2007, A&A, in press, astro-ph/0701244).

Although we cannot exclude that two different sources were active at the same time, we regard this as unlikely. We, therefore, suggest that IGR J17453-2853 and Granat 1741.9-2853 are one and the same source.

We note that the other source active in the Galactic Center region, Swift J174535.5-290135.6 (ATels #1005, #1006), was still seen during our observations on February 17 (about 13 mCrab, 8 sigma, JEM-X 3-10 keV) and February 20 (about 15 mCrab, 9 sigma, JEM-X 3-10 keV).