juliensimon/gravitational-lenses

Strong Gravitational Lens Catalog

Part of the Astronomy Datasets collection on Hugging Face.

A comprehensive catalog of 32,838 confirmed and probable strong gravitational lenses compiled by the lenscat project. Covers both galaxy-scale and cluster-scale lenses drawn from dozens of surveys and publications.

Dataset description

Strong gravitational lensing occurs when a massive foreground object (a galaxy or galaxy cluster) bends the light of a background source so severely that multiple images, arcs, or Einstein rings are produced. This catalog consolidates discoveries from major surveys including SDSS, DES, HSC, CLASH, RELICS, and many others into a single machine-readable table.

Each entry records the lens name, sky coordinates, lens redshift (when measured), morphological type (galaxy or cluster), a confidence grading, and a literature reference.

Schema

Column	Type	Description
name	string	Lens system name / identifier
ra_deg	float64	Right ascension (J2000, degrees)
dec_deg	float64	Declination (J2000, degrees)
lens_redshift	float64	Spectroscopic redshift of the lens (null if unmeasured)
lens_type	string	Morphological type: "galaxy" or "cluster"
grading	string	Confidence level: "confident" or "probable"
reference	string	Discovery / catalog reference (URL or bibcode)

Quick stats

• 32,838 strong gravitational lenses
• 31,755 galaxy-scale lenses, 1,023 cluster-scale lenses
• 2,309 confident, 30,529 probable
• 13,974 lenses with measured redshifts (range 0.000 -- 3.000, median 0.480)

Usage

from datasets import load_dataset

ds = load_dataset("juliensimon/gravitational-lenses", split="train")
df = ds.to_pandas()

# Sky distribution
import matplotlib.pyplot as plt
plt.scatter(df["ra_deg"], df["dec_deg"], s=0.2, alpha=0.3)
plt.xlabel("RA (deg)")
plt.ylabel("Dec (deg)")
plt.title("Strong Gravitational Lenses -- Sky Distribution")
plt.gca().invert_xaxis()
plt.show()

# Redshift distribution
df["lens_redshift"].dropna().hist(bins=60)
plt.xlabel("Lens Redshift")
plt.ylabel("Count")
plt.title("Lens Redshift Distribution")
plt.show()

# Galaxy vs cluster breakdown
df["lens_type"].value_counts().plot.bar()
plt.title("Lens Type Distribution")
plt.show()

# Confident vs probable by type
df.groupby(["lens_type", "grading"]).size().unstack().plot.bar()
plt.title("Grading by Lens Type")
plt.show()

Data source

Compiled by the lenscat project, which consolidates strong lens discoveries from the literature into a single catalog. See the project repository for the full list of contributing surveys and references.

Pipeline

Source code: juliensimon/space-datasets

Citation

@dataset{gravitational_lenses,
  author = {Simon, Julien},
  title = {Strong Gravitational Lens Catalog},
  year = {2026},
  publisher = {Hugging Face},
  url = {https://huggingface.co/datasets/juliensimon/gravitational-lenses},
  note = {Based on the lenscat project (https://github.com/lenscat/lenscat)}
}

License

CC-BY-4.0