Fermi Large Area Telescope Fourth Source Catalog Data Release 4 (4FGL-DR4)

TL;DR

This paper introduces the 4FGL-DR4 gamma-ray source catalog from Fermi-LAT, updating data, sources, and associations based on 14 years of observations, with new sources and refined source information.

Contribution

It provides an updated gamma-ray source catalog with new sources, improved source data, and refined associations based on extended observations and analysis methods.

Findings

Contains 7194 gamma-ray sources from 14 years of data.

Adds four new extended sources and updates existing ones.

Includes 546 new point sources, with 8 identified and 229 plausible counterparts.

Abstract

We present an incremental version (4FGL-DR4, for Data Release 4) of the fourth Fermi-LAT catalog containing 7194 gamma-ray sources. Based on the first 14 years of science data in the energy range from 50 MeV to 1 TeV, it uses the same analysis methods as the 4FGL-DR3 catalog did for 12 years of data, with only a few improvements. The spectral parameters, spectral energy distributions, light curves and associations are updated for all sources. We add four new extended sources and modify two existing ones. Among the 6658 4FGL-DR3 sources, we delete 14 and change the localization of 10, while 32 are newly associated, eleven associations are changed and three associations are discarded. We add 546 point sources, among which 8 are considered identified and 229 have a plausible counterpart at other wavelengths. Most are just above the detection threshold, and 14 are transient sources below the detection threshold that can affect the light curves of nearby sources.