The Fermi Large Area Telescope

The Large Area Telescope (LAT), the primary instrument on the Fermi Gamma-ray Space Telescope, is an imaging, wide field-of-view gamma-ray telescope. After many improvements to the data acquisition and event analysis procedures, it now covers the broad energy range from ∼20 MeV to ∼2 TeV. After more than 13 years of operation since its launch in June 11, 2008, it has provided the best-resolved and deepest portrait of the gamma-ray sky. In this chapter we review the design of the instrument, the data acquisition system, calibration, and performance.