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INTEGRAL shows MAXI J1659-152 further declines in hard X-rays

ATel #2890; E. Kuulkers (ESA/ESAC, Spain), J. Alfonso-Garzon (LAEX-CAB/INTA-CSIC, Spain), V. Beckmann (APC, France), T. Bird (Southampton, UK), S. Brandt (DTU Space, Denmark), J. Chenevez (DTU Space, Denmark), T. Courvoisier (ISDC, Switzerland), M. Del Santo (INAF/IASF-Roma, Italy), 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), K. Pottschmidt (UMBC/NASA GSFC, USA), C. Sanchez-Fernandez (ESA/ESAC, Spain), R. Wijnands (UvA, The Netherlands)
on 30 Sep 2010; 16:36 UT
Credential Certification: Erik Kuulkers (ekuulker@rssd.esa.int)

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

We report on INTEGRAL observations as part of the Galactic bulge monitoring program (see ATel #438, #2875) on the recently discovered X-ray transient MAXI J1659-152 (Negoro et al. 2010, ATel #2873; Mangano et al. 2010, GCN #11296). Data were obtained between UT 29 September 09:55 and 13:37.

The hard X-ray flux continues to decline in the 20-40 keV band with respect to that seen on September 28 (Kuulkers et al. 2010, ATel #2888): during our observations the average flux is about 150 mCrab. The source is not detected at higher energies. We infer a 40-100 keV upper limit of 10-15 mCrab. This shows a rapid softening of the source with respect to the previous INTEGRAL observations on September 25/26 and 28 (Vovk et al. 2010, ATel #2875; Kuulkers et al. 2010, ATel 2888), and may indicate that the source is leaving the transitional phase from the hard to soft state (Kalamkar et al. 2010, ATel #2881).

The next observation of the Galactic bulge monitoring program starts on 2 October 2010 10:17 UT.