GLAST (Gamma-ray Large Area Space Telescope), renamed the Fermi Gamma-ray Space Telescope, is an orbiting high-energy astrophysics observatory designed to map the universe in gamma rays with up to 100 times the sensitivity, resolution, and coverage of previous missions. It carries two instruments: the Large Area Telescope, sensitive to gamma rays in the 200 MeV to 300 GeV range, and the Burst Monitor, for detecting gamma-ray bursts.

Following a one-year sky survey, GLAST became available to scientists for particular research projects. An international mission led by NASA, GLAST was launched on 11 June 2008.