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INTEGRAL sees IGR J17544-2619 active again

ATel #2820; E. Kuulkers (ESA/ESAC, Spain), J. Chenevez (DNSC, Denmark), J. Alfonso-Garzon (LAEX-CAB/INTA-CSIC, Spain), V. Beckmann (ISDC, Switzerland), T. Bird (Southampton, UK), S. Brandt (DNSC, Denmark), T. Courvoisier (ISDC, Switzerland), A. Domingo (LAEX-CAB/INTA-CSIC, Spain), K. Ebisawa (ISAS, Japan), P. Jonker (SRON, The Netherlands), P. Kretschmar (ESA/ESAC, Spain), C. Markwardt (GSFC, USA), T. Oosterbroek (ESA/ESTEC, The Netherlands), A. Paizis (INAF-IASF, Italy), C. Sanchez-Fernandez (ESA/ESAC, Spain), R. Wijnands (UvA, The Netherlands)
on 30 Aug 2010; 13:25 UT
Distributed as an Instant Email Notice Request For Observations
Credential Certification: Erik Kuulkers (ekuulker@rssd.esa.int)

Subjects: X-ray, Request for Observations, Binary, Neutron Star, Transient, Variables

INTEGRAL Galactic bulge monitoring observations (see, e.g., ATels #438 and #1266) between UT 29 Aug 2010 22:54 and 30 Aug 2010 02:35 revealed X-ray flaring from the Supergiant Fast X-ray Transient (SFXT) IGR J17544-2619. Its last activity was reported about 180 days ago, in March 2010 (ATel #2463).

IGR J17544-2619 flared on time scales of about half an hour, from around a peak IBIS/ISGRI count rate of 60 +/- 10 mCrab (18-40 keV) during an 1800-sec pointing down to about 10 mCrab, i.e., near the half-an-hour detection limit. The average IBIS/ISGRI detection significance over the 12.6 ksec observation is about 19 sigma (18-40 keV). The behaviour is similar to that seen during its previous detected activity by INTEGRAL (e.g., ATel #1266, #1697).

JEM-X detects IGR J17544-2619 too, at 22 +/- 12 mCrab (3-10 keV, 3 sigma), and 40 +/- 22 mCrab (10-25 keV, 4 sigma), over the course of the observation.

Since activity at other wavelengths is expected (see, e.g., ATel #2475) we encourage follow-up observations. The next INTEGRAL Galactic bulge monitoring observation is expected to start at UT 4 Sep 2010 11:26.

The INTEGRAL Galactic bulge monitoring results (JEM-X and IBIS/ISGRI light curves and mosaic images) are publicly available at http://isdc.unige.ch/Science/BULGE/.