astro-legacy-archive/class-released-products

CLASS released measurement products

The preview renders the released Q_POLARISATION field from class_dr1_40GHz_skymap_n128 in its source RING order.

This dataset contains LAMBDA's three CLASS DR1 40 GHz maps, three 90 GHz EE spectra, and 40 GHz circular-polarization limits. Transfer functions, beam, bandpass, simulations, masks, synchrotron-beta and reobserved or combined auxiliary maps, and software are excluded. Configuration names are source filename stems.

How to use

from datasets import load_dataset
dataset = load_dataset("astro-legacy-archive/class-released-products", "class_midell_binned_Cl_EE", split="train[:1]", columns=["lmin", "Cb"])
print(dataset[0]["lmin"], dataset[0]["Cb"])

31.0 0.0002634909

import json
from huggingface_hub import hf_hub_download
import pyarrow.parquet as pq
path = hf_hub_download("astro-legacy-archive/class-released-products", "class_dr1_40GHz_skymap_n128.parquet", repo_type="dataset")
print(json.loads(pq.read_schema(path).metadata[b"healpix_map"])["schema"])

astro-legacy-archive/healpix-map

Maps

Each map configuration is an implicit full-sky HEALPix table with NSIDE=128, 196,608 pixels, RING ordering, celestial/equatorial coordinates (COORDSYS='C'), POLCCONV='COSMO', and healpix-map schema 2.0.0. Its 192 source rows each contain nine fixed-size lists of 1,024 float32 values. Element j of row i is HEALPix pixel i * 1024 + j in RING order.

All three maps preserve these source identifiers and meanings:

identifier	source form	source unit	meaning
V_POLARISATION	1024E	K	Stokes V circular-polarization map
Q_POLARISATION	1024E	K	Stokes Q linear-polarization map
U_POLARISATION	1024E	K	Stokes U linear-polarization map
VV	1024E	sec	VV component of the hits map, proportional to inverse variance for constant white noise
VQ	1024E	sec	VQ component of the hits map, proportional to inverse variance for constant white noise
VU	1024E	sec	VU component of the hits map, proportional to inverse variance for constant white noise
QQ	1024E	sec	QQ component of the hits map, proportional to inverse variance for constant white noise
QU	1024E	sec	QU component of the hits map, proportional to inverse variance for constant white noise
UU	1024E	sec	UU component of the hits map, proportional to inverse variance for constant white noise

The source headers also record OBJECT='FULLSKY', TEMPTYPE='THERMO', STOKES='VQU', FREQ='40 GHz', and RELEASE='DR1'. The map reconstruction promise preserves selected FITS binary-table columns in source column and row order with identical form, shape, dtype, and value bits; FITS container serialization is outside the promise.

Measurement tables

All table columns are float64, preserve source row and column order, and carry statistical-product schema 1.2.0.

configuration	rows	columns and meanings
class_midell_binned_Cl_EE	27	lmin, lmax: dimensionless minimum and maximum multipole in each bin; Cb: binned EE power spectrum C_l; Cberr: error including sample variance
class_midell_binned_Cl_EE_wide	15	the same four identifiers and meanings, with the separately published wider bins
classxplanck_lowell_Cl_EE	29	ell: dimensionless multipole; Cl: CLASS × Planck low-ell EE cross-power spectrum C_l; Clerr: error including sample variance
CLASS_40GHz_vlim	10	Column 1: dimensionless multipole-bin center; Column 2: CLASS 40 GHz VV bandpower; Column 3: 1-sigma uncertainty; Column 4: 95% confidence upper limit

Cb, Cberr, Cl, Clerr, and Column 2 through Column 4 are in uK^2_CMB. The unlabeled circular-polarization table retains Column 1 through Column 4; no descriptive identifiers are substituted.

Embedded table metadata records the complete ASCII header, source URL, size and digest, each field's meaning and unit basis, measurement-to-uncertainty links, and the regeneration command. Canonical ASCII reconstruction preserves source column order, dtype, shape, values, and the header verbatim; numeric whitespace and decimal formatting are outside that promise.

Sources

The release index is the CLASS product table. The pinned inputs checked on 2026-08-30 are:

source	bytes	SHA-256
class_dr1_40GHz_skymap_n128.fits	7,087,680	ba4afc73ed83551927a6d237fc21c7e63e554d87022db059414567101a01ccb3
class_dr1_40GHz_skymap_m1_n128.fits	7,087,680	953e379fd2d7e0fe7abc2f1c640464860d4204cce439cfe27d8f859381b410b6
class_dr1_40GHz_skymap_m2_n128.fits	7,087,680	face4fe290d978fa26dc5617cc305384b60637338e6b3e90ec7658f87c263463
class_midell_binned_Cl_EE.txt	1,590	b073a54bf806dd3ae8e4004a86fa3a156cb2c6fe3a7eb7324958820c67ba35f4
class_midell_binned_Cl_EE_wide.txt	1,061	2d1d177537a3ab5294c5ad77caf0ed83b39549347700117793b0b8e5f225382f
classxplanck_lowell_Cl_EE.txt	1,378	4a7e26d5e1e5e25d084af5fff54ad6a6d1aa1adf805e5709ca19d437e615eb67
CLASS_40GHz_vlim.txt	306	26e5f85ed14c90496f19d94fcbbb0e9ee135fc467e4bf7530c4206740e7d4d77

The checked supporting documents are class_dr1_pol_maps_info.html (11,736 bytes, SHA-256 1c1e2dc81b0bf49ddd92d310ed23e08f0c1fd56b370c38a33f4c887963992a6a), class_90ghz_ee_spectra_info.html (12,265 bytes, SHA-256 47d9d108c7e07b2d8356bf82bfc178ed3e98c87d3248e0006fafaabb09150806), and class_info.html (10,096 bytes, SHA-256 e963f311c11eb3986341a5b377947e1e0f1b07d181a24583015f43af63a5e41f).

Licence, credit, and citations

HEASARC states verbatim:

HEASARC materials are all available freely for your use.

This is a free-use statement rather than a named formal licence.

No explicit licence is published. For the tables, credit, verbatim: “No requested credit line is published.” The map metadata preserves the credit verbatim: “CLASS data release served by LAMBDA.”

Cite the applicable LAMBDA release:

• CLASS Collaboration (2024). 2016-2022 CLASS 40 GHz Products (DR1), Version 1.0, NASA LAMBDA. DOI: 10.71662/80wa-m931.
• CLASS Collaboration (2025). CLASS 90 GHz 2021-2024 Power Spectra, Version 1.0, NASA LAMBDA. DOI: 10.71662/9h5m-1369.
• CLASS Collaboration (2020). Circular Polarization, Version 1.0, NASA LAMBDA. DOI: 10.71662/yxe1-2r86.