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The 2009 Fermi Symposium

The Fermi LAT First Catalog

Jean Ballet, CEA Saclay


The Fermi Large Area Telescope (LAT) has been routinely gathering science data since August 2008, surveying the full sky every three hours. In February 2009 the LAT team released a preliminary list (0FGL) of 205 bright, high-confidence sources, based on the first 3 months of observations. The first source catalog (1FGL), based on 11 months of data, more accurate calibration and a refined model of Galactic diffuse emission, reaches much deeper in flux limit. Beyond including several times more sources, the 1FGL catalog provides more information for each source, such as fluxes in 5 bands and monthly light curves. We will describe the construction of this first catalog, its characteristics, and its limitations.