The Large Area Telescope (LAT) is the primary scientific instrument aboard the Fermi Gamma-ray Space Telescope, launched on June 11, 2008. It is an imaging, wide field-of-view space telescope that detects high-energy gamma rays from extreme astrophysical sources across the universe.
The principal objective of the Large Area Telescope (LAT) is to conduct a long term high sensitivity gamma-ray observations of celestial sources in the energy range from ~20 MeV to >300 GeV. The LAT is a wide field-of-view (FoV) imaging gamma-ray telescope with large effective area combined with good energy and angular resolution. The LAT data are being used for a) rapid notification of gamma-ray transient events and monitoring of variable sources b) constructing a catalog of celestial gamma-ray sources along with spectra and light curves for many of these sources c) localization point sources to 0.3 - 2 arcmin d) spatial mapping and spectra of extended sources such as supernova remnants, molecular clouds, and nearby galaxies e) measuring the diffuse gamma-ray background, f) searching for signals from dark matter and g) measuring the flux and spectrum of cosmic ray electrons.