The GLAST Burst Monitor (GBM).

The selection of the GLAST burst monitor (GBM) by NASA will allow the investigation of the relation between the keV and the MeV-GeV emission from $\gamma$-ray bursts. The GBM consists of 12 NaI and 2 BGO crystals allowing a continuous measurement of the energy spectra of $\gamma$-ray bursts from $\sim 5$ keV to $\sim 30$ MeV. One feature of the GBM is its high time resolution for time-resolved $\gamma$-ray spectroscopy. Moreover the arrangement of the NaI-crystals allows a rapid on-board location ($ < 15^\circ$) of a $\gamma$-ray burst within a FoV of $\sim 8.6$ sr. This position will be communicated to the main instrument of GLAST making follow-up observations at high energies possible. [ABSTRACT FROM AUTHOR]