| --- |
| license: cc-by-4.0 |
| pretty_name: "ICRF3 Celestial Reference Frame" |
| language: |
| - en |
| description: "The third International Celestial Reference Frame (ICRF3) — the fundamental coordinate reference frame for astronomy, defined by extragalactic radio sources observed by VLBI." |
| task_categories: |
| - tabular-classification |
| tags: |
| - space |
| - icrf |
| - reference-frame |
| - astrometry |
| - quasar |
| - vlbi |
| - open-data |
| size_categories: |
| - 1K<n<10K |
| --- |
| |
| # 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 |
| |
| ```python |
| 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](https://vizier.cds.unistra.fr/), CDS Strasbourg. |
| |
| ## Related datasets |
| |
| - [pulsar-catalog](https://huggingface.co/datasets/juliensimon/pulsar-catalog) -- ATNF Pulsar Catalogue |
| - [open-star-clusters](https://huggingface.co/datasets/juliensimon/open-star-clusters) -- Open Star Clusters |
| |
| ## Pipeline |
| |
| Source code: [juliensimon/space-datasets](https://github.com/juliensimon/space-datasets) |
| |
| ## Citation |
| |
| ```bibtex |
| @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](https://creativecommons.org/licenses/by/4.0/) |
| |
