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INTEGRAL resumes monitoring the Galactic bulge: IGR J17329-2731 still active

ATel #11273; E. Kuulkers (ESA/ESTEC, The Netherlands, J. Chenevez (DTU Space, Denmark), A. Bazzano (INAF/IAPS, Italy), V Beckmann (CNRS/IN2P3, France), T. Bird (Southampton, UK), A. Bodaghee (GCSU, USA), M. Del Santo (INAF/IASF-Pa, Italy), A. Domingo (CAB/INTA-CSIC, Spain), P. Jonker (SRON, The Netherlands), P. Kretschmar (ESA/ESAC, Spain), C. Markwardt (GSFC, USA), A. Paizis (INAF/IASF-Mi, Italy), K. Pottschmidt (UMBC/NASA GSFC, USA), C. Sanchez-Fernandez (ESA/ESAC, Spain), R. Wijnands (UvA, The Netherlands)
on 7 Feb 2018; 21:10 UT
Credential Certification: Erik Kuulkers (Erik.Kuulkers@sciops.esa.int)

Subjects: X-ray, Binary, Globular Cluster, Neutron Star, Transient, Variables

On 2018 February 6, INTEGRAL resumed its monitoring program of the Galactic bulge mainly in the 3-100 keV band (see ATel #438; Kuulkers et al. 2007, A&A, 466, 595). The total exposure of the first observation was about 11 ks. The X-ray transients IGR J17329-2731 and GRS 1747-312 were seen to be active by JEM-X.

IGR J17329-2731 was discovered in August 2017 (ATels #10644, #10645, #10682), and is possibly a symbiotic binary (ATel #10685). It has been active since then (Bozzo et al. 2018, submitted). We find it is faint, with a detection significance of about 3 sigma in the mosaic, i.e., close to the detection limit of JEM-X. We derive fluxes of 5.5 +/- 2.7 mCrab and 11 +/- 5 mCrab in the 3-10 keV and 10-25 keV energy bands, respectively. GRS 1747-312 is a frequently recurring neutron-star binary X-ray transient in the globular cluster Terzan 6 (see, e.g., in 't Zand et al. 2003, A&A 406, 233); we find it at 31 +/- 4 mCrab (3-10 keV) and 14 +/- 9 mCrab (10-25 keV).

No significantly active X-ray transients were seen with IBIS/ISGRI, down to a limit of about 20 mCrab (i.e., about 1e36 erg/s at 8 kpc) in the 18-40 keV band.

Further observations of the Galactic bulge within the program are foreseen in the coming months, as well as other INTEGRAL observations aimed at the Galactic Center, see http://integral.esac.esa.int/isocweb/schedule.html?action=schedule&startRevno=1917&endRevno=1950.

INTEGRAL Galactic bulge monitoring program web page