--- license: other license_name: "cc-by-nc-3.0-igo" license_link: "https://creativecommons.org/licenses/by-nc/3.0/igo/" pretty_name: "Planck Second Sunyaev-Zeldovich Source Catalog (PSZ2)" language: - en 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 Com" task_categories: - tabular-classification tags: - space - planck - sunyaev-zeldovich - galaxy-cluster - cmb - esa - cosmology - astronomy - open-data - tabular-data - parquet size_categories: - 1K Hubble Deep Field revealing myriad galaxies across cosmic time

Credit: NASA/ESA/STScI

*Part of a [dataset collection](https://huggingface.co/collections/juliensimon/astronomy-datasets-69c24caf2f17e36128946743) 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 ```python from datasets import load_dataset ds = load_dataset("juliensimon/planck-sz2-clusters", split="train") df = ds.to_pandas() ``` ```python 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](https://huggingface.co/datasets/juliensimon/galaxy-clusters) - [juliensimon/desi-dr1-redshifts](https://huggingface.co/datasets/juliensimon/desi-dr1-redshifts) - [juliensimon/pantheon-plus-sne-ia](https://huggingface.co/datasets/juliensimon/pantheon-plus-sne-ia) > If you find this dataset useful, please consider [giving it a like](https://huggingface.co/datasets/juliensimon/planck-sz2-clusters) on Hugging Face. It helps others discover it. ## About the author Created by [Julien Simon](https://julien.org) — AI Operating Partner at Fortino Capital. Part of the [Space Datasets](https://julien.org/datasets) collection. ## Citation ```bibtex @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](https://creativecommons.org/licenses/by-nc/3.0/igo/)