WMAP

Wilkinson Microwave Anisotropy Probe

Product Name
Processing, intensity and Polarization Exclusion Masks
Mission
WMAP
Coord. System
Galactic
Projection Type
HEALPix, nested

Description

A number of WMAP data analysis applications use pixel masks to exclude foreground-contaminated portions of the sky from the analysis. Diffuse emission in Stokes I (temperature) is masked using a combination of cuts in the K band and Q band maps, as described in Bennett, et.al., 2013. Diffuse emission in Stokes Q and U is masked using cuts in K band polarized intensity combined with a model of thermal dust emission. Point sources are masked based on a combination of external catalog data and WMAP-detected sources. The source exclusion radius is 0.6 degree for the majority of sources in the intensity masks, with the exception that a radius of 1.2 degrees is used for point sources brighter than 5 Jy in any of the WMAP bands. An exclusion radius of 1.0 degrees is used for all but one source in the polarization masks. The exception is Cen A, which is masked to a radius of 3 degrees in polarization.

Mask values for each map pixel are provided in the N_obs field of the data file (the 'Temperature' field should be disregarded). A mask value of zero means the pixel is rejected; a value of one means the pixel is accepted. For temperature analysis, we provide two cut levels: the standard cut ("temperature_kq85") corresponds roughly to the "Kp2" cut in the 3-year data release; the extended cut ("temperature_kq75") corresponds roughly to the "Kp0" cut in the 3-year data release. For all the analysis and processing masks we provide the data at multiple pixel resolutions. For all but the polarization analysis mask, the cut is defined at the lowest supplied resolution and all higher resolution versions mask the same sky area. The polarization analysis mask is defined at Nside=512 (r9) but we also provide a degraded version at Nside=16 (r4) for low-l analysis. For this mask, an r4 pixel is included (set to one) if more than 50% of its daughter r9 pixels are set to one.

The point source catalog mask was used to exclude Galactic plane and Magellanic cloud regions in making the WMAP 9-year point source catalogs. The region outside of this mask consists of pixels that are either outside of the diffuse component of the nine-year KQ85 temperature analysis mask or outside of the seven-year point source catalog mask.

Mask Sky Fraction
Admitted (%)
HEALPix
Nside
Description
Analysis Masks
wmap_temperature_kq75_analysis_mask_r9_9yr_v5.fits 68.8 512 Extended temperature analysis mask
wmap_temperature_kq75_analysis_mask_r10_9yr_v5.fits 68.8 1024 Extended temperature analysis mask
wmap_temperature_kq85_analysis_mask_r9_9yr_v5.fits 74.8 512 Primary temperature analysis mask
wmap_temperature_kq85_analysis_mask_r10_9yr_v5.fits 74.8 1024 Primary temperature analysis mask
wmap_polarization_analysis_mask_r9_9yr_v5.fits 73.2 512 Polarization analysis mask
wmap_polarization_analysis_mask_r4_9yr_v5.fits 73.4 16 Polarization analysis mask
wmap_kp8_mask_r9_9yr_v5.fits 91.9 512 Temperature cleaning mask
wmap_point_source_catalog_mask_r9_9yr_v5.fits 82.8 512 Point source catalog mask
wmap_temperature_source_mask_r9_9yr_v5.fits 94.7 512 Temperature-only Point Source Exclusion Mask
Processing Masks
wmap_processing_mask_K_notyr2_r4_9yr_v5.fits 89.8 16 K-band for all but year 2
wmap_processing_mask_K_notyr2_r9_9yr_v5.fits 89.8 512 K-band for all but year 2
wmap_processing_mask_K_notyr2_r10_9yr_v5.fits 89.8 1024 K-band for all but year 2
wmap_processing_mask_K_yr2_r4_9yr_v5.fits 91.2 16 K-band for year 2
wmap_processing_mask_K_yr2_r9_9yr_v5.fits 91.2 512 K-band for year 2
wmap_processing_mask_K_yr2_r10_9yr_v5.fits 91.2 1024 K-band for year 2
wmap_processing_mask_Ka_r4_9yr_v5.fits 93.1 16 Ka-band
wmap_processing_mask_Ka_r9_9yr_v5.fits 93.1 512 Ka-band
wmap_processing_mask_Ka_r10_9yr_v5.fits 93.1 1024 Ka-band
wmap_processing_mask_Q_r4_9yr_v5.fits 93.5 16 Q-band
wmap_processing_mask_Q_r9_9yr_v5.fits 93.5 512 Q-band
wmap_processing_mask_Q_r10_9yr_v5.fits 93.5 1024 Q-band
wmap_processing_mask_V_r4_9yr_v5.fits 95.9 16 V-band
wmap_processing_mask_V_r9_9yr_v5.fits 95.9 512 V-band
wmap_processing_mask_V_r10_9yr_v5.fits 95.9 1024 V-band
wmap_processing_mask_W_r4_9yr_v5.fits 96.8 16 W-band
wmap_processing_mask_W_r9_9yr_v5.fits 96.8 512 W-band
wmap_processing_mask_W_r10_9yr_v5.fits 96.8 1024 W-band

Year 2 required special handing to avoid extremely low N-Obs in K-band near Jupiter; for year 2 the number of masked pixels were reduced to allow those K maps to achieve convergence.

Additional Information

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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. Alan P. Smale
LAMBDA Director: Dr. David T. Chuss
NASA Official: Dr. David T. Chuss
Web Curator: Mr. Michael R. Greason