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INTEGRAL observations of SAX J1808.4-3658 currently in outburst

ATel #7380; M. Del Santo (INAF/IASF-Palermo, Italy), E. Bozzo (ISDC, Switzerland), E. Kuulkers (ESA/ESAC, Spain), A. Bazzano (INAF/IAPS, Italy), V. Beckmann (APC, France), T. Bird (Univ. of Southampton, UK), A. Bodaghee (GCSU, USA), J. Chenevez (DTU Space, Denmark), A. Domingo (CAB/INTA-CSIC, Spain), P. Jonker (SRON, The Netherlands), P. Kretschmar (ESA/ESAC, Spain), C. Markwardt (GSFC, USA), A. Paizis (INAF/IASF-Milano, Italy), K. Pottschmidt (UMBC/NASA GSFC, USA), C. Sanchez-Fernandez (ESA/ESAC, Spain), R. Wijnands (UvA, The Netherlands)
on 13 Apr 2015; 14:42 UT
Credential Certification: Melania Del Santo (melania@ifc.inaf.it)

Subjects: X-ray, Binary, Neutron Star, Pulsar

Referred to by ATel #: 12964, 12993

The latest INTEGRAL Galactic Bulge monitoring (ATel #438) was performed during revolution 1529 on 2015 April 12 starting at 18:15 UT (57124.761 MJD) for a total of 12462 seconds.
We report on the IBIS/ISGRI detection of the new outburst from the millisecond X-ray pulsar SAX J1808.4-3658 (ATels #7364 #7371 #7376 #7379). The source is detected at about 23 sigma in both 18-40 keV and 40-80 keV IBIS/ISGRI maps with 8.7 ks effective exposure time, and the estimated fluxes are 60+/-3 mCrab and 78+/-3 mCrab in the two energy bands, respectively. SAX J1808.4-3658 was outside the JEM-X and OMC field of view.
The IBIS/ISGRI spectrum extends up to 100 keV and it is well described by a simple power-law model with a photon index of 2.0+/-0.2. The 20-100 keV X-ray flux estimated from the spectral fit is 1.4E-09 erg/cm^2/s.
The INTEGRAL monitoring of the Galactic bulge will also continue in the coming weeks, and the observation results from the near real time data will be made available on the WEB (http://integral.esac.esa.int/BULGE/).