This page provides a preliminary Fermi Large Area Telescope (LAT) list of sources (FL8Y) meant to help in writing 2018 NASA Fermi Guest Investigator proposals. Based on the first eight years of science data from the Fermi Gamma-ray Space Telescope mission and the 100 MeV-1 TeV range, it is the deepest yet in this energy range. Relative to the 3FGL catalog, the FL8Y source list has twice as much exposure as well as a number of analysis improvements, but is lacking an updated model for Galactic diffuse gamma-ray emission. The FL8Y source list includes 5524 sources above 4-sigma significance, with source location regions and spectral properties. Fifty-eight sources are modeled explicitly as spatially extended, and overall 303 sources are considered as identified based on angular extent or correlated variability (periodic or otherwise) observed at other wavelengths. For 2130 sources we have not found plausible counterparts at other wavelengths. More than 2900 of the identified or associated sources are active galaxies of the blazar class, 217 are pulsars. This source list is meant to be replaced within a few months by the official 4FGL catalog which will benefit from an improved model of diffuse emission.
The FL8Y list is meant to provide proposers applying to the Fermi GI program with an updated description of the gamma-ray sky with respect to 3FGL. It contains nearly 2500 new sources which can be used as a starting point for new works.
Being a courtesy effort, FL8Y is neither published nor posted on the arXiv. We request the community users to refrain from publishing works (in particular population studies) using directly material from FL8Y, and wait for the future 4FGL catalog that will soon supersede FL8Y.
The 8-year Source List is currently available as a FITS file. Supporting tools and documentation have been provided and are linked below.
|v4||10 Jan 2018||gll_psc_8year_v4.fit||Corrected mistake in LP_Index column. Other spectral columns have changed slightly, 16 positive flags are now 0 and three 0FGL sources are reported in ASSOC_GAM.|
|v3||03 Jan 2018||gll_psc_8year_v3.fit||Initial Release|