juliensimon/planck-sz2-clusters

Planck Second Sunyaev-Zeldovich Source Catalog (PSZ2)

Credit: NASA/ESA/STScI

Part of a dataset collection on Hugging Face.

Dataset description

Complete catalog of galaxy clusters detected via the thermal Sunyaev-Zeldovich (SZ) effect by the ESA Planck satellite, sourced from NASA HEASARC.

The Sunyaev-Zeldovich (SZ) effect is the inverse Compton scattering of cosmic microwave background (CMB) photons by the hot intracluster medium (ICM) of galaxy clusters. As CMB photons pass through the ICM (electron temperatures of 10^7-10^8 K), they receive a characteristic energy boost that produces a spectral distortion observable at millimeter wavelengths: a decrement below ~217 GHz and an increment above. This effect is unique in cosmology because its surface brightness is redshift-independent, making it an extraordinarily powerful tool for detecting massive clusters at any distance.

The Planck satellite's all-sky survey at nine frequencies (30-857 GHz) provided the first uniform all-sky SZ cluster catalog. The PSZ2 catalog represents the largest SZ-selected sample of galaxy clusters, detected using three independent methods: two implementations of matched multi-frequency filters (MMF1 and MMF3) and PowellSnakes (PwS), a Bayesian detection algorithm. Each cluster's integrated Compton parameter Y5R500 quantifies the total thermal energy of the ICM and serves as a low-scatter mass proxy through the Y-M scaling relation.

These SZ-selected clusters are essential for constraining cosmological parameters (Omega_m, sigma_8), calibrating the cluster mass function, understanding large-scale structure formation, and cross-matching with optical, X-ray, and gravitational lensing surveys.

This dataset is suitable for tabular classification tasks.

Schema

Column	Type	Description	Sample	Null %
name	str	Planck cluster designation in the format 'PSZ2 GXXX.X+/-XX.X', encoding Galactic longitude and latitude in the name	PSZ2 G075.71+13.51	0.0%
ra	float64	ICRS J2000.0 right ascension of the SZ centroid in degrees (0-360)	290.2898594	0.0%
dec	float64	ICRS J2000.0 declination of the SZ centroid in degrees (-90 to +90)	43.9748641	0.0%
lii	float64	Galactic longitude of the SZ centroid in degrees (0-360)	75.71422918	0.0%
bii	float64	Galactic latitude of the SZ centroid in degrees (-90 to +90)	13.51983254	0.0%
snr	float64	Planck SZ detection signal-to-noise ratio; catalog threshold is SNR > 4.5; the most massive clusters can reach SNR > 50	48.98511	0.0%
y5r500	float64	Integrated Compton y-parameter within 5*R_500 in arcmin^2; dimensionless measure of total ICM thermal energy; low-scatter mass proxy; typical range 1e-4 to 1e-2 arcmin^2	0.078309433	0.0%
redshift	float64	Cluster spectroscopic or photometric redshift; null for ~30% of Planck clusters that lack optical/NIR confirmation	0.0557	33.8%
is_confirmed	bool	Derived: True if redshift is not null (cluster has a measured distance); False for unconfirmed SZ candidates	True	0.0%

Quick stats

• 1,653 galaxy clusters detected via the SZ effect
• 1,094 confirmed with measured redshifts (median z = 0.224)
• 559 unconfirmed SZ candidates
• Highest SNR: PSZ2 G075.71+13.51 (SNR = 49.0)
• Median SNR: 5.6, Max SNR: 49.0

Usage

from datasets import load_dataset

ds = load_dataset("juliensimon/planck-sz2-clusters", split="train")
df = ds.to_pandas()

from datasets import load_dataset

ds = load_dataset("juliensimon/planck-sz2-clusters", split="train")
df = ds.to_pandas()

# Confirmed clusters with redshifts
confirmed = df[df["is_confirmed"]]
print(f"{len(confirmed):,} clusters with measured redshifts")

# Highest SNR detections
top = df.nlargest(10, "snr")[["name", "snr", "redshift", "msz"]]
print(top)

# Redshift distribution
import matplotlib.pyplot as plt
df["redshift"].dropna().hist(bins=50)
plt.xlabel("Redshift")
plt.ylabel("Count")
plt.title("Planck SZ2 Cluster Redshift Distribution")
plt.show()

Data source

https://heasarc.gsfc.nasa.gov/W3Browse/all/plancksz2.html

Related datasets

• juliensimon/galaxy-clusters

• juliensimon/desi-dr1-redshifts

• juliensimon/pantheon-plus-sne-ia

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About the author

Created by Julien Simon — AI Operating Partner at Fortino Capital. Part of the Space Datasets collection.

Citation

@dataset{planck_sz2_clusters,
  title = {Planck Second Sunyaev-Zeldovich Source Catalog (PSZ2)},
  author = {juliensimon},
  year = {2026},
  url = {https://huggingface.co/datasets/juliensimon/planck-sz2-clusters},
  publisher = {Hugging Face}
}

License

CC-BY-NC-3.0-IGO