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INTEGRAL sees Swift J174510.8-2624, Swift J1753.7-2544, XTE J1810-189, XTE J1739-285 to be still on, while 1E 1740.7-2942 is off

ATel #4804; E. Kuulkers (ESA/ESAC, Spain), J. Chenevez (DTU Space, Denmark), J. Alfonso-Garzon (CAB/INTA-CSIC, Spain), V. Beckmann (APC, France), T. Bird (Southampton, UK), S. Brandt (DTU Space, Denmark), T. Courvoisier (ISDC, Switzerland), M. Del Santo (INAF/IASF-Roma, Italy), A. Domingo (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), K. Pottschmidt (UMBC/NASA GSFC, USA), C. Sanchez-Fernandez (ESA/ESAC, Spain) & R. Wijnands (UvA, The Netherlands)
on 11 Feb 2013; 14:14 UT
Credential Certification: Erik Kuulkers (ekuulker@rssd.esa.int)

Subjects: X-ray, Binary, Black Hole, Neutron Star, Transient, Variables

Referred to by ATel #: 4899, 4904, 5084, 5332, 13138

A new season of the INTEGRAL Bulge monitoring programme (see ATel #438) started this morning (UT 2013 Feb 11 00:57-04:39). The sources Swift J174510.8-2624 (ATels #4760, #4782), Swift J1753.7-2544 (ATels #4769, #4789), XTE J1810-189 (ATel #4752) and XTE J1739-285 (ATels #4304, #4354) are still active. Swift J174510.8-2624 and Swift J1753.7-2544 are transient black-hole candidate binaries. XTE J1810-189 and XTE J1739-285 are recurrent transient type-I X-ray bursters, and thus hosting neutron stars.

We find the following fluxes for these transient sources:
Swift J174510.8-2624: 29+/-3 mCrab (3-10 keV), 49+/-5 mCrab (10-25keV), 65+/-2 mCrab (18-40 keV), 100+/-2 mCrab (40-100 keV)
Swift J1753.7-2544 : 13+/-5 mCrab (3-10 keV), 32+/-7 mCrab (10-25 keV), 46+/-2 mCrab (18-40 keV), 60+/-2 mCrab (40-100 keV)
XTE J1810-189 : 64+/-3 mCrab (18-40 keV), 37+/-4 mCrab (40-100 keV)
XTE J1739-285 : 88+/-2 mCrab (3-10 keV), 35+/-4 mCrab (10-15 keV), <~10 mCrab (18-40 keV; 6 sigma), <~15 mCrab (40-100 keV; 6 sigma)
Note that XTE J1810-189 was not in the field of view of the JEM-X during the observations.

These observations show Swift J174510.8-2624 (ATels #4760, #4782) and Swift J1753.7-2544 to be (still) in a hard state. No Type I X-ray bursts from XTE J1810-189 and XTE J1739-285 were seen during our INTEGRAL observations.

During our last monitoring season, 1E 1740.7-2942 (the Great Annihilator) was seen to turn off (ATel #4471). Our observation on 2013 Feb 11 shows that it is still below our monitoring detection limits: flux limits are <~7 mCrab (3-10 keV; 3 sigma), <~9 mCrab (10-25 keV; 3 sigma), <~10 mCrab (18-40 keV; 6 sigma), <~15 mCrab (40-100 keV; 6 sigma). We encourage observations at all wavelengths to further investigate the nature of the low states of this source.

INTEGRAL Galactic bulge monitoring program