README.md

---
license: cc-by-4.0
pretty_name: "X-ray Binary Catalog"
language:
  - en
description: "Merged catalog of high-mass and low-mass X-ray binaries from HEASARC (Liu et al. 2006/2007)"
task_categories:
  - tabular-classification
tags:
  - space
  - x-ray-binary
  - hmxb
  - lmxb
  - x-ray
  - astronomy
  - compact-object
  - neutron-star
  - black-hole
  - open-data
  - tabular-data
  - parquet
size_categories:
  - n<1K
configs:
  - config_name: default
    data_files:
      - split: train
        path: data/xray-binaries.parquet
    default: true
---

# X-ray Binary Catalog

<div align="center">
  <img src="banner.jpg" alt="A youthful globular star cluster observed by the Hubble Space Telescope" width="400">
  <p><em>Credit: NASA/ESA/Hubble</em></p>
</div>

*Part of the [Astronomy Datasets](https://huggingface.co/collections/juliensimon/astronomy-datasets-69c24caf2f17e36128946743) and [Stellar Catalogs](https://huggingface.co/collections/juliensimon/stellar-catalogs-69c24caf2f17e36128946744) collections on Hugging Face.*

![Update X-ray Binaries](https://github.com/juliensimon/space-datasets/actions/workflows/update-xray-binaries.yml/badge.svg)
![Updated](https://img.shields.io/badge/dynamic/json?url=https://raw.githubusercontent.com/juliensimon/space-datasets/main/status.json&query=$.xray-binaries&label=updated&color=brightgreen)

Merged catalog of **305** X-ray binaries (116 high-mass, 189 low-mass) from NASA HEASARC,
combining the HMXB catalog (Liu, van Paradijs & van den Heuvel 2006) and the LMXB catalog (Liu, van Paradijs & van den Heuvel 2007).

## Dataset description

X-ray binaries are stellar systems in which a compact object (neutron star or black hole) accretes matter from a
companion star, producing intense X-ray emission. They are divided into two classes based on the mass of the donor star:

- **High-Mass X-ray Binaries (HMXBs)**: The donor is a massive O or B star (typically >10 solar masses). Accretion
  occurs via stellar wind or Roche lobe overflow. HMXBs are found in star-forming regions and include Be/X-ray
  binaries (the largest subclass) and supergiant X-ray binaries.

- **Low-Mass X-ray Binaries (LMXBs)**: The donor is a low-mass star (typically <1 solar mass). Accretion proceeds
  through Roche lobe overflow, forming a bright accretion disk. LMXBs are concentrated toward the Galactic center
  and globular clusters. They include the Z and Atoll sources (classified by their X-ray color-color diagrams) and
  the soft X-ray transients.

X-ray binaries are natural laboratories for studying accretion physics, strong gravity, and the equation of state of
ultra-dense matter. Their X-ray variability (pulsations, quasi-periodic oscillations, thermonuclear bursts) encodes
information about the compact object's mass, spin, and magnetic field. Several black hole mass measurements come from
dynamical studies of X-ray binary orbits.

This dataset merges the two standard reference catalogs maintained at HEASARC, providing a unified view of the known
Galactic X-ray binary population with positions, X-ray fluxes, orbital periods, and companion star classifications.

## Schema

| Column | Type | Description |
|--------|------|-------------|
| `__row` | string |  |
| `name` | string | Source designation / common name |
| `xray_type` | string |  |
| `ra` | float | Right ascension (J2000, degrees) |
| `dec` | float | Declination (J2000, degrees) |
| `lii` | string | Galactic longitude (degrees) |
| `bii` | string | Galactic latitude (degrees) |
| `position_type` | string |  |
| `optical_name` | string |  |
| `ref_optical` | string |  |
| `vmag_limit` | string |  |
| `vmag` | string | Visual magnitude of the optical counterpart |
| `vmag_min` | string |  |
| `vmag_flag` | string |  |
| `bv_color` | string |  |
| `bv_color_flag` | string |  |
| `bv_color_max` | string |  |
| `ub_color` | string |  |
| `reddening` | string |  |
| `reddening_max` | string |  |
| `reddening_flag` | string |  |
| `ref_photometry` | string |  |
| `jmag` | string |  |
| `hmag_limit` | string |  |
| `hmag` | string |  |
| `kmag_limit` | string |  |
| `kmag` | string |  |
| `fx_limit` | string |  |
| `fx` | string |  |
| `fx_max` | string |  |
| `fx_range` | string |  |
| `ref_fx` | string |  |
| `porb` | string |  |
| `porb_flag` | string |  |
| `pulse_per` | string |  |
| `pulse_per_flag` | string |  |
| `ref_periods` | string |  |
| `spect_type` | string |  |
| `alt_name_1` | string |  |
| `alt_name_1_flag` | string |  |
| `alt_name_2` | string |  |
| `alt_name_3` | string |  |
| `class` | string | Source classification (e.g., Be/X, SFXT, Atoll, Z) |
| `__x_ra_dec` | string |  |
| `__y_ra_dec` | string |  |
| `__z_ra_dec` | string |  |
| `binary_type` | string | Binary type: HMXB or LMXB |
| `ref_optical_name` | string |  |
| `reddening_limit` | string |  |
| `flux_limit` | string |  |
| `flux` | float | X-ray flux (mCrab or source-specific units) |
| `flux_max` | string |  |
| `flux_range` | string |  |
| `ref_flux` | string |  |
| `pulse_period` | string |  |
| `lmxb_notes` | string |  |

## Quick stats

- **305** X-ray binaries total
- **116** High-Mass X-ray Binaries (HMXB)
- **189** Low-Mass X-ray Binaries (LMXB)

## Usage

```python
from datasets import load_dataset

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

# Count by type
print(df["binary_type"].value_counts())

# HMXBs vs LMXBs
hmxb = df[df["binary_type"] == "HMXB"]
lmxb = df[df["binary_type"] == "LMXB"]
print(f"{len(hmxb):,} HMXBs, {len(lmxb):,} LMXBs")

# Sky distribution
import matplotlib.pyplot as plt
fig, ax = plt.subplots(figsize=(12, 6))
for btype, group in df.groupby("binary_type"):
    ax.scatter(group["ra"], group["dec"], s=5, alpha=0.7, label=btype)
ax.set_xlabel("RA (deg)")
ax.set_ylabel("Dec (deg)")
ax.legend()
ax.set_title("X-ray Binary Sky Distribution")
```

## Data source

All data comes from the HEASARC X-ray binary catalogs:
- [HMXB Catalog (hmxbcat)](https://heasarc.gsfc.nasa.gov/W3Browse/all/hmxbcat.html) — Liu, van Paradijs & van den Heuvel (2006)
- [LMXB Catalog (lmxbcat)](https://heasarc.gsfc.nasa.gov/W3Browse/all/lmxbcat.html) — Liu, van Paradijs & van den Heuvel (2007)

Accessed via the HEASARC TAP protocol.

## Update schedule

Quarterly (February, May, August, November 1st at 08:00 UTC) via [GitHub Actions](https://github.com/juliensimon/space-datasets).

## Related datasets

- [pulsar-catalog](https://huggingface.co/datasets/juliensimon/pulsar-catalog) — ATNF Pulsar Catalog
- [mcgill-magnetar-catalog](https://huggingface.co/datasets/juliensimon/mcgill-magnetar-catalog) — McGill Magnetar Catalog
- [chandra-x-ray-sources](https://huggingface.co/datasets/juliensimon/chandra-x-ray-sources) — Chandra Source Catalog
- [gravitational-wave-events](https://huggingface.co/datasets/juliensimon/gravitational-wave-events) — LIGO/Virgo GW Events

## Pipeline

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

## Support

If you find this dataset useful, please give it a heart on the [dataset page](https://huggingface.co/datasets/juliensimon/xray-binary-catalog) and share feedback in the Community tab! Also consider giving a star to the [space-datasets](https://github.com/juliensimon/space-datasets) repo.

## Citation

```bibtex
@dataset{xray_binary_catalog,
  author = {Simon, Julien},
  title = {X-ray Binary Catalog},
  year = {2026},
  publisher = {Hugging Face},
  url = {https://huggingface.co/datasets/juliensimon/xray-binary-catalog},
  note = {Based on HEASARC HMXB (Liu et al. 2006) and LMXB (Liu et al. 2007) catalogs}
}
```

## License

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