Fermi Summer School will be May 26 to June 5, 2026.
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.
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
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.
Fermi Observations for MW 959
Mission Week 959 begins with a continuation of the -50 deg. modified sine profile from the previous week. Then, on DOY 288 (2026-10-15) at 01:03 UT a 10-minute freeze observation occurs during which a -50 deg. modified sine profile is loaded. Next, on DOY 292 (2026-10-19) at 16:58 UT a 10-minute freeze observation occurs during which an asymmetric -50/+60 deg. profile is loaded. This profile continues until the end of the mission week. The survey repeat period DECREASED from 5665s to 5664s. Note that positive rock angles are south, and negative rock angles are north.
The Fermi Science Support Center (FSSC) runs the guest investigator program, creates and maintains the mission time line, provides analysis tools for the scientific community, and archives and serves Fermi data.
Guest Investigator Program - Details of the Cycle 19 Call for Proposals, deadline Jan 29 2026.
Targets of Opportunity (ToO) - How to apply for a ToO.
New Users - Overview of Fermi analysis basics.
Data & Products - Download Fermi data and access data products such as catalogs.
Analysis Tools - Tools from the FSSC and the user community.
Analysis Threads - Step-by-step guides to various types of analyses that you can do with Fermi data.
Multiwavelength Coordination and Existing Data - Links to related datasets and coordination resources.
The Observatory - Key information about Fermi and its capabilities required for analysis.
Research Highlights - Major Fermi research areas and links to publications and press releases.
Transient Science - Resources for transient and time domain science.
Fermi Users' Group - External advisory body that provides input and perspectives from relevant science communities and members to the Fermi Project.
Fermi Summer School - Annual summer school aimed at graduate students and post-doctoral researchers.
Fermi Meetings - Links to summer schools, symposia, and workshops.
News and Mailing List - Sign up for Fermi news and other lists
