- ID:
- ivo://nasa.heasarc/fermilac
- Title:
- Fermi LAT Fourth AGN Catalog
- Short Name:
- FERMILAC
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This is the third update to the fourth catalog of active galactic nuclei (AGNs) detected by the Fermi Large Area Telescope (LAT). This version (4LAC-DR3) derives from the third data release of the 4FGL catalog based on 12 years of gamma-ray data with energies greater than 50 MeV. The spectral parameters, spectral energy distributions (SEDs), yearly light curves, and associations have been updated for all sources. The catalog contains includes 3407 AGN located at high Galactic latitudes (|b| > 10 degrees). This database table was first ingested by the HEASARC in February 2010. It was last updated (to the 4LAC-DR3 version) in June 2023 using electronic data obtained from the Fermi Science Support Center (FSSC). That data is available at <a href="https://fermi.gsfc.nasa.gov/ssc/data/access/lat/4LACDR3/">https://fermi.gsfc.nasa.gov/ssc/data/access/lat/4LACDR3/</a>. Note that this table does not contain the low-latitude sources given in a separate file there, which are not formally a part of the catalog. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/fermilasp
- Title:
- Fermi LAT Monitored Source List
- Short Name:
- FERMILASP
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Fermi LAT table of monitored sources provides daily and weekly fluxes for sources of interest as described in <a href="http://fermi.gsfc.nasa.gov/ssc/data/policy/LAT_Monitored_Sources.html">http://fermi.gsfc.nasa.gov/ssc/data/policy/LAT_Monitored_Sources.html</a>. In addition, similar information will be released for any source which flares above 2x10<sup>-6</sup> photons cm<sup>-2</sup> s<sup>-1</sup> until the flux drops below 2x10<sup>-7</sup> photons cm<sup>-2</sup> s<sup>-1</sup>. Fermi is currently in survey mode and observes the entire sky every day. However, if a source does not exceed the detection threshold, no entry will appear in this catalog. The tabulated fluxes are derived at the LAT Instrument Science Operations center in a 'quick look' analysis to produce results quickly to facilitate follow-up multi-wavelength observations of flaring sources. The table of released fluxes will be updated as analysis and calibrations improve. <b>These early flux estimates do not include systematic uncertainties and do not</b> <b>have an absolute flux calibration</b>. Use of these data as absolute flux measurements for constraining models or for comparison to other data is strongly discouraged at this time. In addition to overall normalization uncertainties, source fluxes may have variations of up to 10% due to currently-uncorrected dependencies of the gamma-ray detection efficiency on variations of the particle background in orbit. Please note that these results are produced using preliminary instrument response functions and calibrations. The quality and stability of these results will improve when updated calibrations become available over the coming months. This database table is created by the HEASARC from FITS tables received from the Fermi Science Support Center (FSSC). The ASP FITS files are produced by the LAT Instrument Science Operations Center (LISOC) and transferred from the LISOC to the FSSC about once per week. This is a service provided by NASA HEASARC .
