The Galactic bulge extends from the Galactic centre to a radius of about 3 kpc, and so spans the central 40 degrees of our Galaxy, corresponding to a distance of about 10000 light years. The region at its very heart, near the nucleus of the Galaxy, is one of the most dynamic places in the Milky Way. Since its launch INTEGRAL has kept close watch on the ever-changing high-energy landscape of the bulge. From 2005 onwards three and a half hour 'snapshot' observations are done approximately every three days (once per orbit), whenever it is visible to INTEGRAL, as part of the Galactic bulge monitoring program.
On February 21 a new season of the monitoring began again as the Galactic bulge came into visibility again. As a service to the scientific community, light curves for all the sources in the field in two high energy bands, as well as JEM-X and IBIS/ISGRI images are publicly available at http://isdc.unige.ch/Science/BULGE/.
As part of the 100 hours of Astronomy activity of the International Year of Astronomy 2009 (astronomy2009.esa.int), a competition will be run based on the monitoring program. Participants must retrieve and analyse data from the INTEGRAL Galactic bulge web page with the aim of investigating the variability of various objects on a number of time scales. The competition is aimed at senior high-school to University level students, and it will run from mid-March to mid-August. More information will be given, as soon as it is available.
The movie presented here spans the entire monitoring program, from its beginning in early 2005 up to October 2008, and illustrates how amazingly variable the face of the Galactic centre at high energies really is, as sources appear and disappear, brighten and fade away of a wide range of time scales. For example, this monitoring campaign has caught a moment of rare quiet in this turbulent region, in april 2006, and allowed us to see an entirely different view when the most prominent hard X-ray emitting sources in the central degrees had all faded to undetectable levels (see POM January 2007 and ESA Press Release: `INTEGRAL sees the Galactic Centre playing hide and seek').
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The POM Archive
A service of ESA/ISOC