juliensimon/sumss-radio-catalog

Sydney University Molonglo Sky Survey (SUMSS)

The Sydney University Molonglo Sky Survey (SUMSS) at 843 MHz, the southern-sky complement to NVSS. Observed with the Molonglo Observatory Synthesis Telescope (MOST), covering declinations south of -30 deg. Contains 211,050 discrete radio sources.

Dataset description

SUMSS is a deep radio survey at 843 MHz covering 8,100 square degrees of the southern sky (declination < -30 deg) with 45 x 45 cosec|dec| arcsecond resolution. It fills the gap left by northern-hemisphere surveys like NVSS and FIRST, providing a matched-sensitivity southern radio catalog essential for all-sky studies.

Schema

Column	Type	Description
ra_deg	float64	Right ascension J2000 (degrees)
dec_deg	float64	Declination J2000 (degrees)
peak_flux_mjy	float64	Peak flux density (mJy/beam)
integrated_flux_mjy	float64	Integrated flux density (mJy)
e_integrated_flux_mjy	float64	Error on integrated flux (mJy)
major_axis_arcsec	float64	Fitted major axis FWHM (arcsec)
minor_axis_arcsec	float64	Fitted minor axis FWHM (arcsec)
position_angle_deg	float64	Position angle (degrees)
deconv_major_arcsec	float64	Deconvolved major axis (arcsec)
deconv_minor_arcsec	float64	Deconvolved minor axis (arcsec)
deconv_pa_deg	float64	Deconvolved position angle (degrees)
mosaic_name	string	Mosaic image name
is_resolved	bool	True if deconvolved major axis > 0

Quick stats

• 211,050 radio sources at 843 MHz
• 0 resolved sources (0.0%)
• Median peak flux: 18.90 mJy/beam
• Sky coverage: RA 0.0--360.0 deg, Dec -89.9---26.0 deg

Usage

from datasets import load_dataset

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

# Flux distribution
import matplotlib.pyplot as plt
df["peak_flux_mjy"].clip(upper=500).hist(bins=200, log=True)
plt.xlabel("Peak flux at 843 MHz (mJy/beam)")
plt.ylabel("Count")
plt.title("SUMSS Source Flux Distribution")
plt.show()

# Sky coverage (southern sky)
plt.scatter(df["ra_deg"], df["dec_deg"], s=0.01, alpha=0.1)
plt.xlabel("RA (deg)")
plt.ylabel("Dec (deg)")
plt.title("SUMSS Sky Coverage (843 MHz, Dec < -30)")
plt.show()

# Resolved vs unresolved
print(f"Resolved: {df['is_resolved'].sum():,}")
print(f"Unresolved: {(~df['is_resolved']).sum():,}")

Data source

Mauch, T., Murphy, T., Buttery, H.J., Curran, J., Hunstead, R.W., Piestrzynski, B., Robertson, J.G., and Sadler, E.M. (2003), SUMSS: A wide-field radio imaging survey of the southern sky. II. The source catalogue. Monthly Notices of the Royal Astronomical Society, 342, 1117. Via VizieR CDS Strasbourg (VIII/81B).

Pipeline

Source code: juliensimon/space-datasets

Citation

@dataset{sumss_radio_catalog,
  author = {Simon, Julien},
  title = {Sydney University Molonglo Sky Survey (SUMSS)},
  year = {2026},
  publisher = {Hugging Face},
  url = {https://huggingface.co/datasets/juliensimon/sumss-radio-catalog},
  note = {Based on Mauch et al. (2003) via VizieR CDS Strasbourg}
}

License

CC-BY-4.0