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Announcement of INTEGRAL Galactic Bulge monitoring program and (re)brightening of GRO J1655-40

ATel #438; E. Kuulkers (ESA/ESAC, Spain), S. Shaw (ISDC, Geneva), A. Paizis (ISDC Geneva/IASF Milano), N. Mowlavi, T. Courvoisier (ISDC, Geneva), K. Ebisawa (NASA/GSFC, USA), P. Kretschmar (ESA/ESAC, Spain), C. Markwardt (NASA/GSFC, USA),T. Oosterbroek, A. Orr (ESA/ESTEC, Netherlands) & R. Wijnands (UvA, Netherlands)
on 8 Mar 2005; 15:19 UT
Credential Certification: Erik Kuulkers (ekuulker@rssd.esa.int)

Subjects: X-ray, Gamma Ray, Binary, Black Hole, Globular Cluster, Neutron Star, Soft Gamma-ray Repeater, Transient, Variables

The Galactic Bulge is a region rich in bright and variable high-energy X-ray and gamma-ray sources. From February 17, 2005 and onwards we will observe this region regularly, using the European gamma-ray satellite INTEGRAL, during all the Galactic Bulge visibility periods under an approved AO-3 proposal (PI: Kuulkers). One complete hexagonal dither pattern (7 pointings of 1800 sec each) is performed during each INTEGRAL revolution (i.e., every 3 days). As a service to the scientific community, the IBIS/ISGRI and JEM-X light curves in two energy bands (20-60 keV, 60-150 keV and 3-10 keV, 10-25 keV, respectively) of the sources detected in the field of view, as well as IBIS/ISGRI mosaic images, are made publicly available as soon as possible after the observations are performed. The results, as well as more information about the program, can be retrieved from http://isdc.unige.ch/Science/BULGE/.

As a first result, we report that the recently active black-hole X-ray transient GRO J1655-40 (ATel #414, and following ATels) has increased considerably in flux on 2005 March 8.0-8.2 (~225 mCrab; 20-60 keV), with respect to our observations on March 2.5-2.7 (~65 mCrab; 20-60 keV) and March 5.7-5.9 (~125 mCrab; 20-60 keV), as well as previous INTEGRAL observations (ATel #422, #432). This supports the recent (re)brightening reported by RXTE (ATel #436).