The FERMI gamma ray satellite, is in orbit, since June 2008. After a commissioning period is now delivering data.
The Large Area Telescope (LAT), onboard of FERMI, is the most sensitive gamma-ray detector to date, in the 20 MeV – 300GeV energy band. It provides large effective collection area (>8000cm2@1GeV), wide field of view (>2sr) and good energy resolution (8%@1GeV). The very large field of view will make it possible to observe 20% of the sky at any instant, and the entire sky on a timescale of a few hours.
Fermi is opening a new and important window on a wide variety of phenomena, including black holes and active galactic nuclei; the optical-UV extragalactic background light, gamma-ray bursts; the origin of cosmic rays and supernova remnants; and searches for hypothetical new phenomena such as supersymmetric dark matter annihilations and Lorentz invariance violation.