README.md

---
license: cc-by-4.0
pretty_name: "AAVSO Variable Star Index (VSX)"
language:
  - en
description: "AAVSO Variable Star Index (VSX) catalog with 10,300,820 variable stars including types, periods, magnitudes, and spectral classifications."
task_categories:
  - tabular-classification
  - tabular-regression
tags:
  - space
  - variable-stars
  - aavso
  - vsx
  - astronomy
  - open-data
  - tabular-data
size_categories:
  - 1M<n<10M
configs:
  - config_name: default
    data_files:
      - split: train
        path: data/aavso_vsx_variable_stars.parquet
    default: true
---

# AAVSO Variable Star Index (VSX)

*Part of the [Astronomy Datasets](https://huggingface.co/collections/juliensimon/astronomy-datasets-69c24caf2f17e36128946743) collection on Hugging Face.*

The AAVSO Variable Star Index (VSX) is the most comprehensive catalog of variable stars,
containing **10,300,820** entries with variable star classifications, photometric properties,
periods, and spectral types. VSX is maintained by the American Association of Variable Star
Observers and is the standard reference for variable star research.

## Dataset description

VSX aggregates variable star data from hundreds of surveys and catalogs worldwide including
OGLE, ASAS-SN, ZTF, Gaia, and AAVSO observer submissions. Each entry represents a unique
variable or suspected variable star with its variability type, brightness range, period (if
known), epoch, and spectral classification.

Of the 10,300,820 entries, **4,830,314** have a measured period and
**10,292,210** have a variability classification.

## Key columns

| Column | Type | Description |
|--------|------|-------------|
| `aavso_uid` | Int64 | AAVSO unique object identifier |
| `name` | string | Primary designation |
| `ra_deg` | float64 | Right ascension J2000 (degrees) |
| `dec_deg` | float64 | Declination J2000 (degrees) |
| `variable_type` | string | Variability type (e.g., EW, SR, RRAB, DSCT) |
| `var_flag` | Int64 | Variability flag (0=confirmed, 1=suspected) |
| `mag_max` | float64 | Maximum brightness (magnitude at max light) |
| `mag_max_passband` | string | Passband for max magnitude |
| `mag_min` | float64 | Minimum brightness / amplitude |
| `mag_min_passband` | string | Passband for min magnitude |
| `min_is_amplitude` | string | Y if mag_min is amplitude, not absolute magnitude |
| `period_days` | float64 | Period in days |
| `epoch_jd` | float64 | Epoch of maximum/minimum (Julian Date) |
| `spectral_type` | string | Spectral classification |
| `mag_range` | float64 | Derived magnitude range (mag_min - mag_max) |

Full schema includes 22 columns with uncertainty flags and limit flags.

## Top variability types

| Type | Count |
|------|-------|
| `ROT` | 2,352,208 |
| `E` | 1,987,833 |
| `L` | 1,604,633 |
| `RS` | 719,268 |
| `DSCT|GDOR|SXPHE` | 717,928 |
| `S` | 493,290 |
| `EW` | 397,843 |
| `SR` | 323,058 |
| `VAR` | 310,300 |
| `RRAB` | 189,791 |

## Quick stats

- **10,300,820** variable star entries
- **4,830,314** with measured period (46.9%)
- **10,292,210** with variability classification (99.9%)
- RA range: 0.0001 to 360.0000 degrees
- Dec range: -89.9288 to 89.9038 degrees

## Usage

```python
from datasets import load_dataset

ds = load_dataset("juliensimon/aavso-vsx-variable-stars", split="train")
df = ds.to_pandas()

# Eclipsing binaries with known periods
eclipsing = df[df["variable_type"].str.startswith("E", na=False) & df["period_days"].notna()]
print(f"Eclipsing binaries with periods: {len(eclipsing):,}")

# Period-amplitude diagram for RR Lyrae
rrab = df[df["variable_type"] == "RRAB"]
import matplotlib.pyplot as plt
plt.scatter(rrab["period_days"], rrab["mag_range"], s=0.5, alpha=0.3)
plt.xlabel("Period (days)")
plt.ylabel("Amplitude (mag)")
plt.title("RR Lyrae (RRAB) Period-Amplitude Diagram")
plt.show()

# Sky distribution
plt.hexbin(df["ra_deg"], df["dec_deg"], gridsize=200, mincnt=1)
plt.colorbar(label="Star count")
plt.xlabel("RA (deg)")
plt.ylabel("Dec (deg)")
plt.title("VSX Variable Stars Sky Density")
plt.show()
```

## Data source

Watson, C.L., Henden, A.A., & Price, A. (2006), *The International Variable Star Index (VSX).*
Society for Astronomical Sciences 25th Annual Symposium on Telescope Science, p. 47.
Maintained by AAVSO: [https://www.aavso.org/vsx/](https://www.aavso.org/vsx/)

## Pipeline

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

## Citation

```bibtex
@dataset{aavso_vsx_variable_stars,
  author = {Simon, Julien},
  title = {AAVSO Variable Star Index (VSX)},
  year = {2026},
  publisher = {Hugging Face},
  url = {https://huggingface.co/datasets/juliensimon/aavso-vsx-variable-stars},
  note = {Based on AAVSO VSX (Watson et al. 2006)}
}
```

## License

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