{
  "abstract": "We used 14 years of Fermi-Large Area Telescope (LAT) data to derive a catalog of sources detected between 20 MeV and 200 MeV. For each source we provide localization, spectral, and association information. The Second Catalog of Low-Energy Fermi-LAT sources (2FLE) contains 450 sources detected at $TS>25$, with median energy flux of $F_{20-200 \\, \\text{MeV}} = 1.9\\times10^{-11}$ erg cm$^{-2}$ s$^{-1}$. Using a Bayesian and likelihood-ratio method, we associate 377 2FLE sources with a known counterpart. Of the 325 objects associated with extragalactic sources, the dominant source class represented in the 2FLE are flat-spectrum radio quasars (FSRQ). Additionally, 52 sources are associated with Galactic sources. Three associated sources have not been previously detected in any $γ$-ray catalog and represent new $γ$-ray sources of known origin. We find that 387 2FLE sources have a positional cross-match with the 4FGL-DR4 sources. For the sources with a 4FGL counterpart, we compare the spectrum of the 2FLE source to the 4FGL spectral energy distributions. Of the 73 2FLE sources without multi-wavelength associations, 13 have a 4FGL counterpart that lacks classification, while 60 are newly discovered $γ$-ray sources. Among these 60 sources, 51 are found at high latitudes ($|b|>10^{\\circ}$), and 38 are detected at $>10σ$. Additionally, we find that out of the 450 2FLE sources 45 are TeV emitters, and 6 are spatially coincident with a 1LHAASO source. The 2FLE helps us pave the way for reducing the ``MeV gap\", and provides the most sensitive catalog between 20-200 MeV to date.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.18972",
  "author_total": 133,
  "authors": [
    {
      "name": "A Adelfio"
    },
    {
      "name": "M Ajello"
    },
    {
      "name": "E Aviano"
    },
    {
      "name": "L Baldini"
    },
    {
      "name": "J Ballet"
    },
    {
      "name": "C Bartolini"
    },
    {
      "name": "D Bastieri"
    },
    {
      "name": "J. Becerra Gonzalez"
    },
    {
      "name": "R Bellazzini"
    },
    {
      "name": "E Bissaldi"
    },
    {
      "name": "R.D Blandford"
    },
    {
      "name": "R Bonino"
    },
    {
      "name": "P Bruel"
    },
    {
      "name": "S Buson"
    },
    {
      "name": "R.A Cameron"
    },
    {
      "name": "S Capecchiacci"
    },
    {
      "name": "P.A Caraveo"
    },
    {
      "name": "F Casaburo"
    },
    {
      "name": "F Casini"
    },
    {
      "name": "E Cavazzuti"
    },
    {
      "name": "N Cibrario"
    },
    {
      "name": "S Ciprini"
    },
    {
      "name": "O Coban"
    },
    {
      "name": "G Cozzolongo"
    },
    {
      "name": "P. Cristarella Orestano"
    },
    {
      "name": "F Cuna"
    },
    {
      "name": "A Cuoco"
    },
    {
      "name": "S Cutini"
    },
    {
      "name": "F d'Ammando"
    },
    {
      "name": "P de la Torre Luque"
    },
    {
      "name": "D Depalo"
    },
    {
      "name": "N Di Lalla"
    },
    {
      "name": "A Dinesh"
    },
    {
      "name": "L Di Venere"
    },
    {
      "name": "A Domínguez"
    },
    {
      "name": "J Eagle"
    },
    {
      "name": "C Fernandez-Suarez"
    },
    {
      "name": "E.C Ferrara"
    },
    {
      "name": "A Fiori"
    },
    {
      "name": "A Franckowiak"
    },
    {
      "name": "Y Fukazawa"
    },
    {
      "name": "S Funk"
    },
    {
      "name": "P Fusco"
    },
    {
      "name": "F Gargano"
    },
    {
      "name": "S Garrappa"
    },
    {
      "name": "C Gasbarra"
    },
    {
      "name": "D Gasparrini"
    },
    {
      "name": "S Germani"
    },
    {
      "name": "F Giacchino"
    },
    {
      "name": "N Giglietto"
    },
    {
      "name": "M Giliberti"
    },
    {
      "name": "F Giordano"
    },
    {
      "name": "M Giroletti"
    },
    {
      "name": "I.A Grenier"
    },
    {
      "name": "S Guiriec"
    },
    {
      "name": "R Gupta"
    },
    {
      "name": "M Hashizume"
    },
    {
      "name": "E Hays"
    },
    {
      "name": "J.W Hewitt"
    },
    {
      "name": "A. Holzmann Airasca"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/891dzj5rtfzx7.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.18972",
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  "id": "891dzj5rtfzx7",
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  "landing_url": "https://hal.science/hal-05843901v1",
  "language": "en",
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
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  "metadata_licence": "CC0-1.0",
  "native_subjects": [
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      "openalex",
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  "pdf_url": "https://arxiv.org/pdf/2610.18972",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-13",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/891dzj5rtfzx7.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:03Z",
      "native_id": "hal-05843901",
      "source": "hal",
      "url": "https://hal.science/hal-05843901v1"
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    {
      "first_seen": "2026-10-30T12:29:31Z",
      "native_id": "2610.18972",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.18972"
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  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.HE",
      "subfield": "high-energy-astrophysics"
    },
    {
      "field": "physics",
      "origin": "hal:0.phys",
      "subfield": "general"
    }
  ],
  "title": "The Second Catalog of Low-Energy Fermi-LAT Sources",
  "title_text": "The Second Catalog of Low-Energy Fermi-LAT Sources",
  "type": "preprint",
  "updated_at": "2026-10-31T12:20:56Z",
  "url": "https://research.draconitic.com/paper/891dzj5rtfzx7",
  "venue": "HAL",
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}