INTEGRAL/JEM-X detects a new outburst of the Rapid Burster (MXB 1730-335)

ATel #4848; J. Chenevez (DTU Space, Denmark), E. Kuulkers (ESA/ESAC, Spain), J. Alfonso-Garzon (CAB/INTA-CSIC, Spain), V. Beckmann (APC, France), T. Bird (Southampton, UK), S. Brandt (DTU Space, Denmark), M. Del Santo (INAF/IAPF-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-Fernández (ESA/ESAC, Spain), R. Wijnands (UvA, The Netherlands)
on 1 Mar 2013; 16:34 UT
Credential Certification: Jerome CHENEVEZ (jerome@space.dtu.dk)

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The neutron star X-ray transient MXB 1730-335, aka the Rapid Burster, has been detected in outburst by the JEM-X monitors onboard INTEGRAL during the Galactic Bulge monitoring (see ATel #438) observation performed on February 28^th, 2013, between (UT) 14:28 and 18:10. It is detected at 25 σ in the combined JEM-X mosaic with an effective exposure time of 2 ksec, and the measured fluxes are the following:
170 ±6 mCrab (2.9e-9 erg/cm²/s) in the 3-10 keV energy band,
122 ±13 mCrab (1.5e-9 erg/cm²/s) in the 10-25 keV energy band.
The source is not visible in the IBIS/ISGRI camera with flux upper limits (6 σ) of ~3 mCrab (2.9e-11 erg/cm²/s) in the 18-40 keV band, and ~10 mCrab (1.0e-10 erg/cm²/s) in the 40-100 keV band.

No bursting activity is noticeable.

During the previous observation of the Galactic Bulge on February 24^th (see ATel #4840) the source was not detected with 5 σ upper limits of 8 mCrab (1.1e-10 erg/cm²/s) and 5 mCrab (5e-11 erg/cm²/s) in the 3-10 keV and 10-25 keV bands, respectively. The last outburst we saw was in September 2011 (ATel #3646), but the Swift/BAT seems to have seen the source active last time in November 2012. The next INTEGRAL observation of the Galactic Bulge is planned for March 11^th.