juliensimon/open-star-clusters

---
license: cc-by-4.0
pretty_name: "Open Star Clusters (Hunt & Reffert 2024)"
language:
- en
description: "The most comprehensive Gaia-era catalog of open star clusters from Hunt & Reffert (2024). Sourced via VizieR CDS Strasbourg."
task_categories:
- tabular-classification
tags:
- space
- star-cluster
- open-cluster
- gaia
- astronomy
- open-data
size_categories:
- 1K<n<10K
---

# Open Star Clusters (Hunt & Reffert 2024)

The most comprehensive Gaia-era catalog of open star clusters, containing **7,167** clusters
with positions, distances, ages, and membership counts derived from Gaia DR3.

## Dataset description

Open clusters are gravitationally bound groups of stars that formed together from the same
molecular cloud. They are key tracers of Galactic structure, stellar evolution, and the
chemical enrichment history of the Milky Way disk. This catalog from Hunt & Reffert (2024)
represents the most complete census of open clusters in the Gaia era, combining automated
detection with careful validation.

Each entry includes sky coordinates, distance, parallax, age, extinction, number of members,
and radial velocity where available.

## Schema

| Column | Type | Description |
|--------|------|-------------|
| `ra_deg` | float64 | Right ascension J2000 (degrees) |
| `dec_deg` | float64 | Declination J2000 (degrees) |
| `distance_pc` | float64 | Distance (parsecs) |
| `parallax_mas` | float64 | Parallax (milliarcseconds) |
| `log_age` | float64 | Logarithmic age (log10 years) |
| `extinction_av` | float64 | Visual extinction A_V (mag) |
| `n_members` | float64 | Number of identified members |
| `radial_velocity_kms` | float64 | Radial velocity (km/s) |

## Quick stats

- **7,167** open clusters
- **0** with age estimates
- **5,749** with radial velocities

## Usage

```python
from datasets import load_dataset

ds = load_dataset("juliensimon/open-star-clusters", split="train")
df = ds.to_pandas()

# Nearby clusters (< 500 pc)
nearby = df[df["distance_pc"] < 500].sort_values("distance_pc")
print(f"{len(nearby):,} clusters within 500 pc")

# Young clusters (< 10 Myr)
young = df[df["log_age"] < 7.0]
print(f"{len(young):,} clusters younger than 10 Myr")
```

## Data source

Hunt, E.L. & Reffert, S. (2024), "Improving the open cluster census. III. Using Gaia DR3",
A&A, 686, A42. Accessed via [VizieR](https://vizier.cds.unistra.fr/), CDS Strasbourg.

## Related datasets

- [gcvs-variable-stars](https://huggingface.co/datasets/juliensimon/gcvs-variable-stars) -- General Catalogue of Variable Stars
- [pulsar-catalog](https://huggingface.co/datasets/juliensimon/pulsar-catalog) -- ATNF Pulsar Catalogue

## Pipeline

Source code: [juliensimon/space-datasets](https://github.com/juliensimon/space-datasets)

## Citation

```bibtex
@dataset{open_star_clusters,
author = {Simon, Julien},
title = {Open Star Clusters (Hunt & Reffert 2024)},
year = {2026},
publisher = {Hugging Face},
url = {https://huggingface.co/datasets/juliensimon/open-star-clusters},
note = {Based on Hunt & Reffert (2024), A&A, 686, A42 via VizieR CDS Strasbourg}
}
```

## License

[CC-BY-4.0](https://creativecommons.org/licenses/by/4.0/)