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The Fermi Gamma-ray Burst Monitor (GBM)

The GBM detector system consists of twelve single NaI detectors mounted in bunches of three detectors on each corner of the Fermi satellite, and of two BGO detectors mounted on opposite sides of the spacecraft.

This GBM detector system detects gamma-ray bursts and sends this information immediately to an international network of observing sites including other satellites (and the Fermi main instrument LAT). This enables immediate follow up observations. GBM itself measures spectra and lightcurves of those bursts in the energy range 10 keV to 30 MeV with high time resolution (0.256 s normal and 0.064 s during bursts).

GBM is a collaborative project between scientists of the MSFC in Huntsville, the University of Alabama in Huntsville and the MPE in Garching.

The MPE was responsible for the development of the detectors and the power supplies of the GBM. The detectors have been built by Jena-Optronik GmbH in Jena (Germany) and the power supplies have been built by Astrium in Friedrichshafen (Germany). In summer 2005 the detectors and the power supplies of the GBM were delivered to NASA and subsequently tested in great detail. In 2006 they were delivered to the manufacturer of the whole Fermi spacecraft (SpectrumAstro (now General Dynamics) in Phoenix, Arizona) and were then integrated with Fermi. In May 2007 the environmental tests, and in September the vibration tests have commenced there. The final thermal vacuum test was completed at the Naval Research Laboratory in Washington, DC in winter 2007/2008. Finally, in spring 2008, the whole satellite was shiped to Florida. Launch into earth orbit occured on June 11, 2008.

Location of the GBM detectors on the Fermi Gamma-ray Space Telescope structure	GBM mounted on the Fermi Gamma-ray Space Telescope (similar view as the drawing left; image: Ben Cooper)