FERMI3FGL ivo://nasa.heasarc/fermi3fgl NASA/GSFC HEASARC Fermi LAT Team 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source The Fermi LAT 4-Year Point Source Catalog (3FGL) is a catalog of high-energy gamma-ray sources detected by the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (Fermi) mission during the first 48 months of the science phase of the mission, which began on 2008 August 4. Compared to the 2FGL catalog, the 3FGL catalog incorporates twice as much data as well as a number of analysis improvements, including improved calibrations at the event reconstruction level, an updated model for Galactic diffuse gamma-ray emission, a refined procedure for source detection, and improved methods for associating LAT sources with potential counterparts at other wavelengths. Sources were detected and characterized in the 100 MeV to 300 GeV range. Source detection was based on a threshold likelihood Test Statistic of 25, corresponding to a significance of just over 4 sigma. This catalog includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits with three different spectral forms; power-law for most sources, log-parabola for significantly curved sources, and power-law with exponential cutoff for known gamma-ray pulsars. It also includes flux measurements in 5 bands for each source. The Fermi LAT Team has evaluated the populations of gamma-ray sources that are represented in the catalog using a protocol defined before launch. Individual LAT-detected sources have been provided identifications or plausible associations with sources in other astronomical catalogs. Care was taken to characterize the sensitivity of the results to the model of interstellar diffuse gamma-ray emission used to model the bright foreground, and a number of sources at low Galactic latitudes and toward bright local interstellar clouds are flagged as having positions that are strongly dependent on the model or as potentially entirely due to incorrectly modeled structure in the Galactic diffuse emission. This catalog has been superseded by the <a href="fermilpsc.html">Fermi LAT 14-Year Point Source Catalog</a>, also known as 4FGL. Please refer to that if you want the latest version. This database table was originally ingested by the HEASARC in May, 2015, as FERMILPSC. With the release of the 4FGL catalog in March, 2019, this catalog was renamed FERMI3FGL. The electronic data for this catalog was obtained from the Fermi Science Support Center (FSSC) at <a href="http://fermi.gsfc.nasa.gov/ssc/data/access/lat/4yr_catalog/">http://fermi.gsfc.nasa.gov/ssc/data/access/lat/4yr_catalog/</a>. This is a service provided by NASA HEASARC . 2015ApJS..218...23A https://heasarc.gsfc.nasa.gov/W3Browse/all/fermi3fgl.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=fermi3fgl& GET text/xml 180 99999 true 85.560302734375 -87.6184997558594 0.166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=fermi3fgl GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_fermi3fgl&Action=More+Options&Action=Parameter+Search&ConeAdd=1 FERMI 0.166666666666667 Gamma-ray public fermi3fgl Fermi LAT 4-Year Point Source Catalog name Source Designation meta.id;meta.main char nullable ra Right Ascension degree pos.eq.ra;meta.main double nullable dec Declination degree pos.eq.dec;meta.main double nullable flux_1_100_gev Flux 1 to 100 GeV photon/cm^2/s phot.flux;em.gamma double nullable flux_1_100_gev_error 1-Sigma Uncertainty in Flux 1 to 100 GeV photon/cm^2/s stat.error;phot.flux;em.gamma double nullable spectral_index Best Fit for the Photon Number Power-Law Index spect.index double nullable spectral_index_error 1-Sigma Uncertainty in Photon Spectral Index stat.error;spect.index double nullable detection_significance Source Detection Significance in Gaussian Sigma Units stat.fit.goodness;instr.background double nullable assoc_name_1 Identification or Positional Associations with Potential Counterparts meta.id.assoc char nullable "__x_ra_dec" System unit vector column double nullable "__y_ra_dec" System unit vector column double nullable "__z_ra_dec" System unit vector column double nullable "__row" System index column char nullable powerlaw_index Best Fit Power-Law Index spect.index double nullable flux_100_300_mev_pos_err Flux 100 to 300 MeV Positive Uncertainty photon/cm^2/s stat.error;phot.flux;em.gamma double nullable nufnu_3_10_gev Energy Flux Density 3 to 10 GeV erg/cm^2/s phot.flux.density;em.gamma double nullable alt_gammaray_name_6 Corresponding Source in the 2FGL Catalog (If Any) meta.id.assoc char nullable assoc_name_3 Identification with Extended Source Counterparts meta.id.assoc char nullable flux_10_100_gev Flux 10 to 100 GeV photon/cm^2/s phot.flux;em.gamma double nullable flux_density_error 1-Sigma Uncertainty on Differential Flux at Pivot Energy photon/cm^2/MeV/s stat.error;phot.flux.density double nullable exp_index_error 1-Sigma Error on Exp_Index stat.error;spect.index double nullable alt_gammaray_name_5 Corresponding Source in the 1FGL Catalog (If Any) meta.id.assoc char nullable flux_1_3_gev_pos_err Flux 1 to 3 GeV Positive Uncertainty photon/cm^2/s stat.error;phot.flux;em.gamma double nullable assoc_name_2 Identification or Positional Associations with Potential Counterparts meta.id.assoc char nullable analysis_flags Flags Indicate Possible Issues in Detection or Characterization of Source meta.code.qual short nullable tevcat_flag Flag Indicates Possible Association with TeVCat meta.code char nullable flux_peak_error 1-Sigma Uncertainty in Peak Flux photon/cm^2/s stat.error;phot.flux;em.gamma double nullable alt_gammaray_name_7 Corresponding Source in the 1FHL Catalog (If Any) meta.id.assoc char nullable flux_peak Peak Integrated Flux from 100 MeV to 100 GeV photon/cm^2/s phot.flux;em.gamma double nullable flux_30_100_mev_pos_err Flux 30 to 100 MeV Positive Uncertainty photon/cm^2/s stat.error;phot.flux;em.gamma double nullable alt_gammaray_name_2 Designation of the Likely Corresponding Source from 1AGL Catalog (If Any) meta.id.assoc char nullable alt_gammaray_name_1 Corresponding Source in Fermi Bright Source List (If Any) meta.id.assoc char nullable nufnu_10_100_gev Energy Flux Density 10 to 100 GeV erg/cm^2/s phot.flux.density;em.gamma double nullable flux_0p3_1_gev_neg_err Flux 0.3 to 1 GeV Negative Uncertainty photon/cm^2/s stat.error;phot.flux;em.gamma double nullable bii Galactic Latitude degree pos.galactic.lat double nullable semi_minor_axis_95 Semi-Minor Axis of Error Ellipse at 95% Confidence (degrees) degree phys.size.sminAxis;pos.errorEllipse double nullable source_type Primary Classification of Source src.class char nullable pivot_energy Energy at Which Error on Differential Flux Is Minimal MeV em.energy double nullable sqrt_ts_1_3_gev Square Root of Likelihood Test Statistic for Flux 1 to 3 GeV stat.likelihood;phot.flux double nullable exp_index Second Index for PLSuperExpCut Type spect.index double nullable cutoff Cutoff Energy for PLExpCutoff Type em.energy double nullable flux_100_300_mev Flux 100 to 300 MeV photon/cm^2/s phot.flux;em.gamma double nullable flux_density Differential Flux at Pivot Energy photon/cm^2/MeV/s phot.flux.density double nullable variability_index Measure of the Source Variability src.var.index double nullable spectrum_type Spectral Type (PowerLaw, LogParabola, PLExpCutoff) char nullable curve_significance Measure of Compatibility with Power Law stat.fit.goodness double nullable semi_major_axis_68 Semi-Major Axis of Error Ellipse at 68% Confidence (degrees) degree phys.size.smajAxis;pos.errorEllipse double nullable flux_3_10_gev_neg_err Flux 3 to 10 GeV Negative Uncertainty photon/cm^2/s stat.error;phot.flux;em.gamma double nullable nufnu_100_300_mev Energy Flux Density 100 to 300 MeV erg/cm^2/s phot.flux.density;em.gamma double nullable alt_gammaray_name_4 Designation of the Likely Corresponding Source from EGR Catalog (If Any) meta.id.assoc char nullable sqrt_ts_3_10_gev Square Root of Likelihood Test Statistic for Flux 3 to 10 GeV stat.likelihood;phot.flux double nullable lii Galactic Longitude degree pos.galactic.lon double nullable flux_3_10_gev Flux 3 to 10 GeV photon/cm^2/s phot.flux;em.gamma double nullable position_angle_68 Position Angle of the 68% Semi-Major Axis, East of North (degrees) degree pos.posAng;pos.errorEllipse double nullable flux_0p3_1_gev Flux 0.3 to 1 GeV photon/cm^2/s phot.flux;em.gamma double nullable sqrt_ts_100_300_mev Square Root of Likelihood Test Statistic for Flux 100 to 300 MeV stat.likelihood;phot.flux double nullable nufnu_0p3_1_gev Energy Flux Density 0.3 to 1 GeV erg/cm^2/s phot.flux.density;em.gamma double nullable sqrt_ts_30_100_mev Square Root of Likelihood Test Statistic for the 30-100MeV Flux stat.likelihood;phot.flux double nullable beta Curvature Parameter for LogParabola Type spect.index double nullable flux_10_100_gev_pos_err Flux 10 to 100 GeV Positive Uncertainty photon/cm^2/s stat.error;phot.flux;em.gamma double nullable beta_error 1-Sigma error on Beta stat.error;spect.index double nullable nufnu_1_3_gev Energy Flux Density 1 to 3 GeV erg/cm^2/s phot.flux.density;em.gamma double nullable flux_30_100_mev_neg_err Flux 30 to 100 MeV Negative Uncertainty photon/cm^2/s stat.error;phot.flux;em.gamma double nullable sqrt_ts_0p3_1_gev Square Root of Likelihood Test Statistic for Flux 0.3 to 1 GeV stat.likelihood;phot.flux double nullable nufnu_30_100_mev Energy Flux Density 30 to 100 MeV erg/cm^2/s phot.flux.density;em.gamma double nullable energy_flux_error 1-Sigma Error in Energy Flux from 100 MeV to 100 GeV erg/cm^2/s stat.error;phot.flux double nullable flux_1_3_gev_neg_err Flux 1 to 3 GeV Negative Uncertainty photon/cm^2/s stat.error;phot.flux;em.gamma double nullable alt_gammaray_name_3 Designation of the Likely Corresponding Source from 3EG Catalog (If Any) meta.id.assoc char nullable time_peak_interval Length of Interval in Which Peak Flux Was Measured s time.interval double nullable semi_major_axis_95 Semi-Major Axis of Error Ellipse at 95% Confidence (degrees) degree phys.size.smajAxis;pos.errorEllipse double nullable flux_1_3_gev Flux 1 to 3 GeV photon/cm^2/s phot.flux;em.gamma double nullable flux_10_100_gev_neg_err Flux 10 to 100 GeV Negative Uncertainty photon/cm^2/s stat.error;phot.flux;em.gamma double nullable time_peak Time of Center of Interval in Which Peak Flux Was Measured mjd time.epoch double nullable sqrt_ts_10_100_gev Square Root of Likelihood Test Statistic for Flux 10 to 100 GeV stat.likelihood;phot.flux double nullable semi_minor_axis_68 Semi-Minor Axis of Error Ellipse at 68% Confidence (degrees) degree phys.size.sminAxis;pos.errorEllipse double nullable flux_100_300_mev_neg_err Flux 100 to 300 MeV Negative Uncertainty photon/cm^2/s stat.error;phot.flux;em.gamma double nullable cutoff_error 1-Sigma Error on Cutoff Energy stat.error;em.energy double nullable significance_peak Source Significance in Peak Interval stat.fit.goodness double nullable flux_3_10_gev_pos_err Flux 3 to 10 GeV Positive Uncertainty photon/cm^2/s stat.error;phot.flux;em.gamma double nullable flux_0p3_1_gev_pos_err Flux 0.3 to 1 GeV Positive Uncertainty photon/cm^2/s stat.error;phot.flux;em.gamma double nullable energy_flux Energy Flux from 100 MeV to 100 GeV erg/cm^2/s phot.flux;em.gamma;em.gamma double nullable tevcat_assoc Designation of the Likely Corresponding Source from the TeVCat Catalog (If Any) meta.id.assoc char nullable position_angle_95 Position Angle of the 95% Semi-Major Axis, East of North (degrees) degree pos.posAng;pos.errorEllipse double nullable flux_30_100_mev Flux 30 to 100 MeV photon/cm^2/s phot.flux;em.gamma double nullable