--- license: cc-by-4.0 pretty_name: "Quasar & AGN Catalog" language: - en description: "Catalog of quasars and active galactic nuclei from SIMBAD -- quasars, Seyfert galaxies, blazars, and LINERs with positions and classifications. Active galactic nuclei are galaxies whose central super" task_categories: - tabular-classification tags: - space - quasar - agn - blazar - seyfert - cosmology - astronomy - simbad - open-data - tabular-data - parquet size_categories: - 10K Deep field image revealing distant galaxies and quasars

Credit: NASA/ESA/STScI

*Part of a [dataset collection](https://huggingface.co/collections/juliensimon/astronomy-datasets-69c24caf2f17e36128946743) on Hugging Face.* ## Dataset description Catalog of quasars and active galactic nuclei from SIMBAD -- quasars, Seyfert galaxies, blazars, and LINERs with positions and classifications. Active galactic nuclei are galaxies whose central supermassive black holes are actively accreting matter, releasing enormous amounts of energy across the electromagnetic spectrum. Quasars, the most luminous subclass, can outshine their entire host galaxy by factors of a hundred or more and are visible at cosmological distances, making them powerful probes of the early universe. The different AGN categories in this catalog -- Seyfert 1 and 2 galaxies, blazars, BL Lac objects, and LINERs -- are thought to represent different viewing angles and accretion rates of the same underlying phenomenon, unified under orientation-dependent models. These objects are critical for multiple areas of astrophysics. Quasars serve as background beacons for studying the intergalactic medium through absorption-line spectroscopy, they anchor the International Celestial Reference Frame (ICRF) used for precision astrometry, and their redshift distribution traces the growth history of supermassive black holes across cosmic time. Blazars, whose relativistic jets point nearly along our line of sight, are among the brightest persistent sources in the gamma-ray sky and are candidate sources of high-energy cosmic neutrinos. The SIMBAD database aggregates classifications from thousands of publications, providing a heterogeneous but broadly representative census of known AGN. This catalog is useful for cross-matching with multi-wavelength surveys, selecting targets for spectroscopic follow-up, and building training sets for machine-learning classification of AGN from photometric data. This dataset is suitable for **tabular classification** tasks. ## Schema | Column | Type | Description | Sample | Null % | |--------|------|-------------|--------|--------| | `name` | str | Primary SIMBAD identifier (e.g. 'QSO J1230+1223' or '3C 273'); unique within SIMBAD but may differ from other catalog designations | 10C J093827+302802 | 0.0% | | `ra_deg` | float64 | Right ascension of the AGN nucleus in the ICRS J2000.0 frame, decimal degrees (0-360) | 144.61387810042916 | 0.0% | | `dec_deg` | float64 | Declination of the AGN nucleus in the ICRS J2000.0 frame, decimal degrees (-90 to +90) | 30.467134118115275 | 0.0% | | `object_type` | str | SIMBAD machine-readable type code: 'QSO' = radio-quiet quasar, 'AGN' = broad-line active galactic nucleus, 'Sy1' = Seyfert 1 (broad + narrow lines, type-1 viewing angle), 'Sy2' = Seyfert 2 (narrow lines only, obscured nucleus), 'BLL' = BL Lac object (featureless continuum, jet pointing toward observer), 'Bla' = blazar (BL Lac or FSRQ with relativistic jet), 'LIN' = LINER (Low Ionization Nuclear Emission Region, weak AGN activity) | AGN | 0.0% | | `agn_category` | str | Human-readable category derived from object_type: one of 'Quasar', 'AGN', 'Seyfert 1', 'Seyfert 2', 'BL Lac Object', 'Blazar', 'LINER'; useful for grouped analysis without parsing SIMBAD codes | Active Galactic Nucleus | 0.0% | ## Quick stats - **50,000** objects total - **11,443** quasars (QSO) - **19,446** Seyfert galaxies (Sy1 + Sy2) - **1,959** blazars / BL Lac objects - **8,643** general AGN - **8,509** LINERs ## Usage ```python from datasets import load_dataset ds = load_dataset("juliensimon/quasar-catalog", split="train") df = ds.to_pandas() ``` ```python from datasets import load_dataset ds = load_dataset("juliensimon/quasar-catalog", split="train") df = ds.to_pandas() # AGN type breakdown print(df["agn_category"].value_counts()) # Sky distribution by type import matplotlib.pyplot as plt for cat in ["Quasar", "Seyfert 1", "BL Lac Object"]: sub = df[df["agn_category"] == cat] plt.scatter(sub["ra_deg"], sub["dec_deg"], s=0.5, alpha=0.3, label=cat) plt.xlabel("RA (deg)") plt.ylabel("Dec (deg)") plt.legend(markerscale=10) plt.title("AGN Sky Distribution by Type") plt.show() ``` ## Data source https://simbad.u-strasbg.fr/simbad/ ## Related datasets - [juliensimon/black-hole-catalog](https://huggingface.co/datasets/juliensimon/black-hole-catalog) - [juliensimon/messier-catalog](https://huggingface.co/datasets/juliensimon/messier-catalog) - [juliensimon/ngc-ic-catalog](https://huggingface.co/datasets/juliensimon/ngc-ic-catalog) - [juliensimon/galaxy-clusters](https://huggingface.co/datasets/juliensimon/galaxy-clusters) > If you find this dataset useful, please consider [giving it a like](https://huggingface.co/datasets/juliensimon/quasar-catalog) on Hugging Face. It helps others discover it. ## About the author Created by [Julien Simon](https://julien.org) — AI Operating Partner at Fortino Capital. Part of the [Space Datasets](https://julien.org/datasets) collection. ## Citation ```bibtex @dataset{quasar_catalog, title = {Quasar & AGN Catalog}, author = {Simon, Julien}, year = {2026}, url = {https://huggingface.co/datasets/juliensimon/quasar-catalog}, note = {Derived from SIMBAD, Centre de Données astronomiques de Strasbourg (CDS), https://simbad.u-strasbg.fr/simbad/}, publisher = {Hugging Face} } ``` ## License [CC-BY-4.0](https://creativecommons.org/licenses/by/4.0/)