Instrumentation for the Gamma-ray Large Area Space Telescope (GLAST) mission

The Gamma-ray Large Area Space Telescope (GLAST) is the next orbiting high-energy gamma-ray mission, scheduled for launch by NASA in 2006. The GLAST Observatory will have two scientific instruments: (1) the Large Area Telescope (LAT), an imaging, wide field-of-view telescope sensitive to radiation over the energy range from similar to20 MeV to more than 300 GeV, and (2) the GLAST Burst Monitor (GBM), sensitive to transient bursts from 10 keV to 25 MeV. The GBM is described elsewhere in this proceedings by Lichti, et al. The LAT, a pair-conversion telescope, is being developed by an international collaboration from the United States, France, Italy, Japan, and Sweden. It will have sensitivity more than 40 times better than that of EGRET. In this paper the LAT instrument, its expected performance, and the current state of its development are described.