CLASS 40 GHz 2016 - 2022 Observations (DR1): Combined Products

Descriptions of the four products are as follows. More details specific to these products are given in Shi et al. (2024).

Combined Data Maps


Coordinate System:
Celestial
Projection Type:
HEALPix, ring, Nside=256
Resolution:
1°

The combined Stokes Q and U maps made with CLASS 40 GHz and WMAP Q-band data. The combined maps cover roughly 73% of the sky, with declination coverage -75° < δ < +29°. Polarization maps are provided in one FITS file that contains the Q and U maps constructed using the CLASS DR1 40 GHz coadd and the 9-year WMAP Q-band data.


Combined Noise Simulations


Coordinate System:
Celestial
Projection Type:
HEALPix, ring, Nside=256
Resolution:
1°

The Stokes Q and U noise simulations for the combined maps, constructed by combining the CLASS DR1 40 GHz noise simulations and the WMAP Q-band noise simulations in the same way as for the data. The CLASS noise simulations can be obtained from the CLASS products on LAMBDA. The WMAP Q-band noise simulations were created (at Nside=256) based on the noise covariance matrices, following the method introduced in Larson et al. (2011). There are 200 noise simulations for the combined maps.


Combined Weights Related


The combined weights related products, including: the inverse of the filtering matrix diagonal, the fractional error on the filtering-matrix-corrected spherical harmonic coefficients, the WMAP Q-band data weights and the CLASS 40 GHz-band data weig hts. The E-modes and B-modes elements are provided at different columns, and are indexed the same as the healpy alm with ℓmax, mmax=383.


Polarized Synchrotron Spectral Index Map


Coordinate System:
Galactic
Projection Type:
HEALPix, ring, Nside=32
Resolution:
7°

The polarized synchrotron spectral index (βs) is determined on 7° scales based on the linear correlation between Q and U maps for the combined maps (40 GHz) and the WMAP K-band (23 GHz). In this analysis, the CLASS 40 GHz and WMAP Q-band maps were iteratively combined after being converted to antenna temperature units at 40 GHz according to the best-fit βs map. Prior to the combination, an estimate of the subdominant thermal dust emission is removed from the CLASS 40 GHz and WMAP Q-band maps. The dust contribution is computed assuming a modified black body spectrum characterized by a Q and U amplitude at 353 GHz (from reobserved Planck PR4 maps for CLASS 40 GHz, and from original Planck PR4 maps for WMAP Q-band), a dust spectral index βd=1.53 and a dust temperature Td=19.6 K were adopted in the calculation.


Additional Information:

Sensitivity-Improved Polarization Maps at 40 GHz with CLASS and WMAP data, Shi et al. (2024)

CLASS Data Pipeline and Maps for 40 GHz Observations through 2022, Li et al. (2023)

CLASS Angular Power Spectra and Map-Component Analysis for 40 GHz Observations through 2022 Eimer et al. (2023)

A service of the HEASARC and of the Astrophysics Science Division at NASA/GSFC
Goddard Space Flight Center, National Aeronautics and Space Administration
HEASARC Director: Dr. Andrew F. Ptak
LAMBDA Director: Dr. Thomas M. Essinger-Hileman
NASA Official: Dr. Thomas M. Essinger-Hileman
Web Curator: Mr. Michael R. Greason