The Fermi Large Area Telescope


      The Fermi Gamma-ray Space Telescope with its main instrument, the Large Area Telescope (LAT), was launched by NASA in June 2008 to survey the gamma-ray sky in the energy range between 20 MeV and several hundreds of GeV. Gamma-ray energies below a few tens of GeV are inaccessible by ground based instruments like Cherenkov telescopes and can only be observed from space. In contrast to pointing telescopes, the LAT is a survey telescope, designed to observe about 20 % of the sky at any time. In its standard "survey mode" operation it makes a sweep through the full sky every 3 hours. The telescope has performed continuous scientific observations since August 2008, with an anticipated mission lifetime of ≥ 10 years.

      The LAT was built and is operated by a large international collaboration of scientists. The LAT works as a pair-creation telescope. Incoming gamma rays convert into an electron-positron pair in the instrument. These charged particles leave traces in the instrument which can be used to determine the direction and the energy of the incoming gamma ray. More detailed information on the instrument can be found on the NASA Fermi website.

      DESY scientists participate in the analysis of LAT data for the following topics:

      • Galactic and extragalactic diffuse gamma-ray emission.
      • Acceleration mechanisms in Supernova Remnants and Pulsar Wind Nebulae.
      • Local cosmic-ray electron & positron spectra.
      • Development of low-background gamma-ray classification techniques.
      • Monitoring the sky for gamma-ray transients.