juliensimon/nvss-radio-catalog

---
license: cc-by-4.0
pretty_name: "NVSS Radio Source Catalog"
language:
- en
description: "NRAO VLA Sky Survey (NVSS) catalog with 1,773,484 discrete radio sources at 1.4 GHz covering 82% of the sky."
task_categories:
- tabular-classification
- tabular-regression
tags:
- space
- radio
- nvss
- vla
- nrao
- astronomy
- 1400mhz
- open-data
size_categories:
- 1M<n<10M
---

# NVSS Radio Source Catalog

The NRAO VLA Sky Survey (NVSS) -- THE foundational 1.4 GHz radio survey covering 82% of the celestial
sky (declination > -40 deg) with **1,773,484** discrete radio sources. This is the most widely
used radio continuum survey in astronomy.

## Dataset description

The NVSS used the VLA in its compact D and DnC configurations to survey the sky north of
declination -40 degrees at 1.4 GHz with ~45" resolution and a completeness limit of about
2.5 mJy. The resulting catalog is the primary reference for radio source populations and
is widely used for cross-matching with optical, infrared, and X-ray catalogs.

## Schema

| Column | Type | Description |
|--------|------|-------------|
| `source_name` | string | NVSS source name (HHMMSS+DDMMSS format) |
| `ra_deg` | float64 | Right ascension J2000 (degrees) |
| `dec_deg` | float64 | Declination J2000 (degrees) |
| `flux_1400mhz_mjy` | float64 | Integrated flux density at 1.4 GHz (mJy) |
| `flux_error_mjy` | float64 | Flux density uncertainty (mJy) |
| `major_axis_arcsec` | float64 | Fitted major axis FWHM (arcsec) |
| `minor_axis_arcsec` | float64 | Fitted minor axis FWHM (arcsec) |
| `position_angle_deg` | float64 | Fitted position angle (degrees) |
| `ra_error_arcsec` | float64 | RA position uncertainty (arcsec) |
| `dec_error_arcsec` | float64 | Dec position uncertainty (arcsec) |
| `residual_code` | string | Residual code from Gaussian fitting |

## Quick stats

- **1,773,484** radio sources
- Median flux density: 5.60 mJy
- Declination range: -40.4 to 89.8 degrees
- Sky coverage: ~82% of the celestial sphere (dec > -40 deg)

## Usage

```python
from datasets import load_dataset

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

# Flux distribution
import matplotlib.pyplot as plt
df["flux_1400mhz_mjy"].clip(upper=1000).hist(bins=200, log=True)
plt.xlabel("Flux density at 1.4 GHz (mJy)")
plt.ylabel("Count")
plt.title("NVSS Source Flux Distribution")
plt.show()

# Sky density map
plt.hexbin(df["ra_deg"], df["dec_deg"], gridsize=100, mincnt=1)
plt.colorbar(label="Source count")
plt.xlabel("RA (deg)")
plt.ylabel("Dec (deg)")
plt.title("NVSS Sky Density")
plt.show()

# Bright sources (> 1 Jy)
bright = df[df["flux_1400mhz_mjy"] > 1000]
print(f"Sources > 1 Jy: {len(bright):,}")
```

## Data source

Condon, J.J., Cotton, W.D., Greisen, E.W., Yin, Q.F., Perley, R.A., Taylor, G.B.,
and Broderick, J.J. (1998), *The NRAO VLA Sky Survey.* Astronomical Journal, 115, 1693.
Via VizieR CDS (VIII/65).

## Pipeline

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

## Citation

```bibtex
@dataset{nvss_radio_catalog,
author = {Simon, Julien},
title = {NVSS Radio Source Catalog},
year = {2026},
publisher = {Hugging Face},
url = {https://huggingface.co/datasets/juliensimon/nvss-radio-catalog},
note = {Based on Condon et al. (1998) via VizieR CDS}
}
```

## License

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