juliensimon/4xmm-dr14-xray-sources
4XMM-DR14 Serendipitous X-ray Source Catalog Credit: NASA/DOE/Fermi LAT Collaboration Part of the Astronomy Datasets collection on Hugging Face. The 4XMM catalog is the largest X-ray source catalog ever produced, containing 630,347 unique X-ray sources detected serendipitously by the European Space Agency's XMM-Newton observatory. This dataset provides the unique-source "slim" version of the catalog (currently DR12s from VizieR), where multiple detections of the same… See the full description on the dataset page: https://huggingface.co/datasets/juliensimon/4xmm-dr14-xray-sources.
4XMM-DR14 Serendipitous X-ray Source Catalog
<div align="center"> <img src="banner.jpg" alt="The gamma-ray sky as seen by NASA's Fermi telescope" width="400"> <p><em>Credit: NASA/DOE/Fermi LAT Collaboration</em></p> </div>
Part of the [Astronomy Datasets](https://huggingface.co/collections/juliensimon/astronomy-datasets-69c24caf2f17e36128946743) collection on Hugging Face.
The 4XMM catalog is the largest X-ray source catalog ever produced, containing 630,347 unique X-ray sources detected serendipitously by the European Space Agency's XMM-Newton observatory. This dataset provides the unique-source "slim" version of the catalog (currently DR12s from VizieR), where multiple detections of the same source have been combined into a single entry with averaged parameters.
Dataset description
XMM-Newton is ESA's flagship X-ray observatory, launched in 1999 and carrying three co-aligned European Photon Imaging Cameras (EPIC) that simultaneously observe the same field. Because the EPIC field of view spans approximately 30 arcminutes, every pointed observation serendipitously detects dozens to hundreds of X-ray sources beyond the intended target. Over more than two decades of operations, this serendipitous survey has built up the most comprehensive census of the X-ray sky ever assembled.
The 4XMM-DR14 catalog is the fourteenth data release of this serendipitous source catalog, compiled by the XMM-Newton Survey Science Centre (SSC) consortium. It covers over 13,000 observations and spans the full 0.2-12 keV energy range of the EPIC cameras. For each unique source, the catalog provides positions, fluxes in five standard energy bands, hardness ratios that encode spectral shape, variability indicators, extent measurements for non-point sources, and quality flags.
The scientific reach of 4XMM is extraordinary. X-ray emission traces the most energetic processes in the universe: accretion onto black holes and neutron stars, million-degree gas in galaxy clusters, coronal activity on stars, and shock-heated plasma in supernova remnants. The catalog contains everything from nearby active stars to distant quasars at cosmological redshifts. It is a primary resource for identifying counterparts to sources detected at other wavelengths, for constructing X-ray luminosity functions, and for discovering rare objects such as tidal disruption events, changing-look AGN, and ultra-luminous X-ray sources.
The five standard energy bands are: band 1 (0.2-0.5 keV), band 2 (0.5-1.0 keV), band 3 (1.0-2.0 keV), band 4 (2.0-4.5 keV), and band 5 (4.5-12.0 keV). Hardness ratios between adjacent bands provide a coarse spectral characterisation without requiring full spectral fitting. Sources detected multiple times have their parameters averaged, and variability between observations is flagged, enabling time-domain studies on timescales from hours to decades.
Schema
Quick stats
- 630,347 unique X-ray sources
- 45 columns after cleanup
- 123,037 sources with multiple detections
- RA range: 0.00 to 360.00 degrees
- Dec range: -88.19 to 89.40 degrees
Usage
from datasets import load_dataset
ds = load_dataset("juliensimon/4xmm-dr14-xray-sources", split="train")
df = ds.to_pandas()
# Brightest sources by total-band flux
if "flux_total" in df.columns:
brightest = df.nlargest(10, "flux_total")[["iau_name", "ra_deg", "dec_deg", "flux_total"]]
print(brightest)
# Sources detected multiple times (variability studies)
multi = df[df["n_detections"] > 5]
print(f"{len(multi):,} sources with >5 detections")
# Sky distribution
import matplotlib.pyplot as plt
fig, ax = plt.subplots(figsize=(14, 7))
ax.scatter(df["ra_deg"], df["dec_deg"], s=0.1, alpha=0.1, c="navy")
ax.set_xlabel("RA (deg)")
ax.set_ylabel("Dec (deg)")
ax.set_title("4XMM-DR14 Sky Coverage")Data source
4XMM-DR14 Serendipitous Source Catalog (Webb N.A. et al., 2020, A&A, 641, A136), compiled by the XMM-Newton Survey Science Centre consortium. Accessed via VizieR (catalog IX/68), CDS Strasbourg.
Update schedule
Static dataset — based on 4XMM-DR14 catalog release.
Related datasets
- chandra-x-ray-sources -- Chandra Source Catalog
- erosita-erass1-xray -- eROSITA eRASS1 X-ray Survey
- swift-bat-hard-xray-survey -- Swift BAT Hard X-ray Survey
Pipeline
Source code: juliensimon/space-datasets
Support
If you find this dataset useful, please give it a ❤️ on the dataset page and share feedback in the Community tab! Also consider giving a ⭐️ to the space-datasets repo.
Citation
@dataset{xmm_4xmm_dr14,
author = {Simon, Julien},
title = {4XMM-DR14 Serendipitous X-ray Source Catalog},
year = {2026},
publisher = {Hugging Face},
url = {https://huggingface.co/datasets/juliensimon/4xmm-dr14-xray-sources},
note = {Based on 4XMM-DR14 (Webb et al. 2020) via VizieR CDS Strasbourg}
}