Fermi-LAT 16-year Source List

TL;DR

The paper presents an updated 16-year Fermi-LAT source catalog, FL16Y, with improved source localization and revised source list based on 16 years of data, enhancing the previous 4FGL-DR4 catalog.

Contribution

It introduces the FL16Y catalog, relocalizing sources with more precise positions and updating source associations after 16 years of Fermi-LAT data.

Findings

Source localization improved by 24% on average.

The catalog includes 7220 sources, an increase from previous versions.

Revised source positions and associations based on extended data.

Abstract

The current Fermi-LAT source catalog (4FGL-DR4: 7194 sources over 14 years) was built incrementally from the 8-year catalog. In a survey mission like Fermi, data accumulate on each source over time, so after 16 years (reached in August 2024) and twice the data for the original 4FGL sources we have more precise localization (by 24% on average). It is thus time to generate a new original catalog, which implies, beyond adding the sources newly detectable after two more years, changing the existing source names (derived from their coordinates) and reviewing the associations. We present an early 16-year list (FL16Y) of 7220 sources, which relocalizes all sources and improves a few aspects of the catalog analysis, but still uses the same model of interstellar diffuse emission as 4FGL-DR4.