Fermi Large Area Telescope Fourth Source Catalog

Understand

We present the fourth Fermi Large Area Telescope catalog (4FGL) of gamma-ray sources.

• Based on the first eight years of science data from the Fermi Gamma-ray Space Telescope mission in the energy range from 50 MeV to 1 TeV, it is the deepest yet in this energy range.
• Relative to the 3FGL catalog, the 4FGL catalog has twice as much exposure as well as a number of analysis improvements, including an updated model for the Galactic diffuse gamma-ray emission, and two sets of light curves (1-year and 2-month intervals).
• The 4FGL catalog includes 5064 sources above 4 sigma significance, for which we provide localization and spectral properties.