Sep 30, 2026

4FHL and GBM Catalog Releases

The FSSC is pleased to announce the official release of the Fourth Fermi-LAT Catalog of High-Energy Sources (4FHL) and the Fermi-GBM SGR/Magnetar Catalog. The 4FHL catalog contains 673 sources detected in the 50 GeV-2 TeV energy range using 16 years of Fermi Large Area Telescope (LAT) observations. The GBM catalog contains 1254 short bursts from 17 years of observations, representing the most comprehensive catalog of magnetar burst activity to date.

July 31, 2026

Fermitools 2.5.3 Released

An updated version (2.5.3) of the Fermitools is now available. This update includes a number of user reported bug fixes and several backend library updates and changes. These changes include the removal of the Xerces-C XML parsing interface and its replacement with the header-only rapidXML interface, moving from python 3.11 to 3.12, and a range of bug fixes reported by users as well as FSSC team members. This update is also fixes a critical bug preventing the accurate generation of radial gaussian and radial disk source maps and patches a performance issue affecting analysis using Fermipy that were found in the previous release (2.5.2).
+ Release Notes

Jun 5, 2026

Data Quality Flag Issue in LAT Spacecraft File

We recently identified an issue with the data quality flag in the LAT spacecraft position and history files. Since the migration to the new SLAC computing cluster in March 2026, the flags set during data quality monitoring have not been propagated into the spacecraft files. As a result, intervals of poor timing resolution were not being correctly flagged with DATA_QUAL=2, which may affect high time resolution analyses such as pulsar studies. There were eight periods (most spanning multiple orbits) on March 17, 20, and 29 and April 5, 8, 16, 20, and 26 that should have been flagged. The issue has been resolved, and the correctly flagged data are now available from the FSSC. If your analysis requires high time resolution, we recommend re-downloading the spacecraft files and reanalyzing your data.