juliensimon/icrf3-reference-frame

ICRF3 Celestial Reference Frame

The third International Celestial Reference Frame (ICRF3) is the fundamental coordinate reference frame for astronomy, adopted by the International Astronomical Union in 2018. It is defined by 4,588 extragalactic radio sources (primarily quasars) observed by Very Long Baseline Interferometry (VLBI). This dataset contains 3,417 sources with variability and structure parameters from the defining catalog.

Dataset description

The ICRF is the realization of the International Celestial Reference System (ICRS) at radio wavelengths. ICRF3 is based on nearly 40 years of VLBI observations and provides the most accurate positions of extragalactic objects, with median positional uncertainties of ~30 microarcseconds for the defining sources. These sources serve as the fixed reference points against which all other celestial positions are measured.

Schema

Column	Type	Description
iers_name	string	IERS designation of the source
ra_deg	float64	Right ascension (degrees, ICRS)
dec_deg	float64	Declination (degrees, ICRS)

Additional columns from the catalog are included with snake_case names.

Quick stats

• 3,417 ICRF3 sources

Usage

from datasets import load_dataset

ds = load_dataset("juliensimon/icrf3-reference-frame", split="train")
df = ds.to_pandas()

# All-sky distribution
print(f"{len(df):,} ICRF3 reference sources")
print(f"RA range: {df['ra_deg'].min():.2f} to {df['ra_deg'].max():.2f} deg")
print(f"Dec range: {df['dec_deg'].min():.2f} to {df['dec_deg'].max():.2f} deg")

Data source

Xu, M.H., Anderson, J.M., Heinkelmann, R., et al. (2019), "Structure Effects for 3417 Celestial Reference Frame Radio Sources", ApJS, 242, 5. Accessed via VizieR, CDS Strasbourg.

Related datasets

• pulsar-catalog -- ATNF Pulsar Catalogue
• open-star-clusters -- Open Star Clusters

Pipeline

Source code: juliensimon/space-datasets

Citation

@dataset{icrf3_reference_frame,
  author = {Simon, Julien},
  title = {ICRF3 Celestial Reference Frame},
  year = {2026},
  publisher = {Hugging Face},
  url = {https://huggingface.co/datasets/juliensimon/icrf3-reference-frame},
  note = {Based on Xu et al. (2019), ApJS, 242, 5 via VizieR CDS Strasbourg}
}

License

CC-BY-4.0