juliensimon/erosita-erass1-xray

eROSITA eRASS1 X-Ray Source Catalog

Credit: NASA/DOE/Fermi LAT Collaboration

Part of a dataset collection on Hugging Face.

Dataset description

The largest X-ray source catalog ever compiled -- sources from the first eROSITA All-Sky Survey (eRASS1), released January 2024.

The extended ROentgen Survey with an Imaging Telescope Array (eROSITA) aboard the Spectrum-Roentgen-Gamma (SRG) satellite performed its first All-Sky Survey (eRASS1) in the 0.2--2.3 keV band, detecting approximately 900,000 X-ray sources across the Western Galactic hemisphere. This is the largest X-ray source catalog ever produced, comprising active galactic nuclei, galaxy clusters, stars, X-ray binaries, and other X-ray-emitting objects.

The soft X-ray band (0.2--2.3 keV) surveyed by eROSITA is dominated by emission from hot plasmas in galaxy clusters, coronally active stars, and accretion onto compact objects. The sheer scale of eRASS1 transforms X-ray astronomy from a regime of targeted observations into genuine survey science: the catalog contains roughly four times more sources than the cumulative total from all previous X-ray missions combined, including ROSAT, XMM-Newton, and Chandra.

Extended sources in this catalog are predominantly galaxy clusters, where the X-ray emission traces the intracluster medium heated to tens of millions of kelvin. Point-like sources are largely active galactic nuclei powered by supermassive black hole accretion, along with stellar coronae and compact binary systems in the Milky Way.

This dataset is suitable for tabular classification tasks.

Schema

Column	Type	Description	Sample	Null %
source_name	str	eROSITA IAU source designation in the format '1eRASS JHHMMSS.s+DDMMSS'	1eRASS J085959.7+000035	0.0%
ra_deg	float64	Right ascension, ICRS J2000.0 (degrees, 0-360); typical positional accuracy a few arcsec	134.99911266908	0.0%
dec_deg	float64	Declination, ICRS J2000.0 (degrees, -90 to +90); eROSITA covers the Western Galactic hemisphere	0.00972498786	0.0%
position_error_arcsec	float64	1-sigma positional uncertainty in arcsec; typically 1-10 arcsec for well-detected sources	5.61993361	0.0%
glon_deg	float64	Galactic longitude (degrees, 0-360)	228.909108448489	0.0%
glat_deg	float64	Galactic latitude (degrees, -90 to +90)	28.2644111206774	0.0%
mjd	float64	Modified Julian Date of the eRASS1 observation epoch (MJD = JD - 2400000.5)	58975.574	0.0%
extent_arcsec	float64	Source spatial extent in arcsec; 0 for point-like sources; >0 indicates extended emission (galaxy clusters have typical values 10-100 arcsec)	0.0	0.0%
is_extended	bool	True if extent_arcsec > 0; extended sources are predominantly galaxy clusters	False	0.0%

Quick stats

• 930,203 X-ray sources
• 26,682 extended sources (galaxy clusters, etc.)
• 903,521 point-like sources (AGN, stars, etc.)

Usage

from datasets import load_dataset

ds = load_dataset("juliensimon/erosita-erass1-xray", split="train")
df = ds.to_pandas()

from datasets import load_dataset

ds = load_dataset("juliensimon/erosita-erass1-xray", split="train")
df = ds.to_pandas()

# Extended sources (galaxy clusters)
clusters = df[df["is_extended"] == True]
print(f"{len(clusters):,} extended sources")

# Sky map
import matplotlib.pyplot as plt
fig, ax = plt.subplots(figsize=(12, 6))
ax.scatter(df["ra_deg"], df["dec_deg"], s=0.01, alpha=0.1)
ax.set_xlabel("RA (deg)")
ax.set_ylabel("Dec (deg)")
ax.invert_xaxis()
ax.set_title("eROSITA eRASS1 X-Ray Sky Map")
plt.show()

Data source

https://vizier.cds.unistra.fr/viz-bin/VizieR?-source=J/A+A/682/A34

Related datasets

• juliensimon/fermi-4fgl-dr4

• juliensimon/pulsar-catalog

• juliensimon/galaxy-clusters

If you find this dataset useful, please consider giving it a like on Hugging Face. It helps others discover it.

About the author

Created by Julien Simon — AI Operating Partner at Fortino Capital. Part of the Space Datasets collection.

Citation

@dataset{erosita_erass1_xray,
  title = {eROSITA eRASS1 X-Ray Source Catalog},
  author = {juliensimon},
  year = {2026},
  url = {https://huggingface.co/datasets/juliensimon/erosita-erass1-xray},
  publisher = {Hugging Face}
}

License

CC-BY-4.0