Continuous brightening of IGR J17473-2721

ATel #1468; C. Baldovin Saavedra (ISDC, Switzerland), J. Chenevez (DTU Space, Denmark), E. Kuulkers (ESA/ESAC, Spain), V. Beckmann (ISDC, Switzerland), A. Bird (Southampton, UK), S. Brandt (DNSC, Denmark), T. J.-L. Courvoisier (ISDC, Switzerland), A. Domingo (LAEFF/INTA, 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), D. Risquez (LAEFF/INTA, Spain), C. Sanchez-Fernandez (ESA/ESAC, Spain), S. Shaw (Southampton, UK/ ISDC, Switzerland), R. Wijnands (UvA, The Netherlands)
on 11 Apr 2008; 08:08 UT
Credential Certification: Volker Beckmann (Volker.Beckmann@obs.unige.ch)

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Renewed accretion activity has been reported by Swift/XRT (ATel #1459), XTE/PCA (ATel #1460) and INTEGRAL/IBIS/ISGRI (ATel #1461) from the RXTE transient IGR J17473-2721 (= XTE J1747-274; ATels #467, #498) after the detection of an X-ray burst by SuperAGILE (ATel #1445). From the on-going Galactic bulge monitoring program (see ATels #1385, #1461) we report that the transient continues to brighten as seen with IBIS/ISGRI and JEM-X.

The average hard X-ray flux during our observations which started on UT 2008 April 08, 10:18 of the source was 111 +/- 1.3 mCrab at 18-40 keV and 111 +/- 2.1 mCrab at 40-100 keV, which represents a flux increase by a factor of about 3 compared with the Galactic bulge observation on 2008 April 1 (ATel #1461). The source is detected with IBIS/ISGRI from 20 up to about 250 keV with an average flux of 2.7e-9 erg/cm**-2/s.

The JEM-X shows the average persistent flux to be 50+/-4 mCrab (3-10 keV) and 90+/-7 mCrab (10-25 keV). We observe a ~50 s long type-I X-ray burst on UT 2008, April 08, 13:36, which reached an unabsorbed peak flux of 3.7E-8 erg/cm**-2/s (~1.5 Crab) as estimated between 0.01-100 keV, and a blackbody temperature of 2.4+/-0.4 keV.

Inspection of the Swift/BAT hard X-ray light curve indicates that the source became progressively brighter in the daily averaged observations from 2008 March 30 onward, 30 mCrab (15-50 keV), increasing up to a flux of ~120 mCrab (15-50 keV) on 2008, April 9.

More information about the INTEGRAL Galactic bulge monitoring