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IGR J17375-3022: a new hard X-ray transient detected by INTEGRAL

ATel #1781; C. Ricci, S. Soldi, V. Beckmann (ISDC), J. M. Miller (Univ. Michigan), M. D. Caballero-Garcia (IoA Cambridge), and E. Kuulkers (ESA/ESAC) on behalf of the Galactic Bulge monitoring team
on 14 Oct 2008; 13:14 UT
Distributed as an Instant Email Notice Request For Observations
Credential Certification: Volker Beckmann (Volker.Beckmann@obs.unige.ch)

Subjects: X-ray, Gamma Ray, Request for Observations, Transient

Referred to by ATel #: 1783, 1810, 2027

The IBIS/ISGRI instrument aboard INTEGRAL discovered a new X-ray source during the second part of the ToO observation on H 1743-322 conducted from 2008 October 10 at 21:35 U.T. to October 11, 22:00. The new source candidate, IGR J17375-3022, is located in the Galactic bulge at (RA,DEC)=(264.3946, -30.3817) (J2000), with a position accuracy of 2.2 arcmin. The source is clearly detected within 82 ksec in the 20-40 keV mosaic image with a significance of 12 sigma, and an average flux of 10 +/- 1 mCrab. At 40-80 keV, IGR J17375-3022 is detected with 6.7 sigma and 7 +/- 1 mCrab. The source is not detectable in any single pointing, each lasting about 2.6 ksec. The source was not detected by JEM-X1 (3-20 keV, 11 ksec effective exposure time), and for SPI the 3 sigma upper limit in the 20-40 keV band is ~18 mCrab. The source is not detectable in the previous revolution, with a 3 sigma upper limit of 4 mCrab, and in the following one, with an upper limit of 6 mCrab (20-40 keV).

The source is detected in ISGRI up to 150 keV and the spectrum can be fit by a single power law model with a photon index of Gamma = 2.0 +/- 0.2. The model flux in the 20-40 keV band is 7e-11 erg/cm^2/sec, and in 20-150 keV it is 2e-10 erg/cm^2/sec. If we assume that the source is at a distance similar to the Galactic centre, this gives a luminosity of L(20-150 keV) = 1.5e+36 erg/sec.

There are no known X-ray sources within the IBIS/ISGRI position uncertainty. According to Simbad there is only one known source in the ISGRI error box: the infrared emitting carbon star IRAS 17345-3021, located 1.8 arcmin away.