Wilkinson Microwave Anisotropy Probe

The data made available through this page has been updated. The most recent version of this data may be accessed through /product/map/current/

The foreground reduced skymaps were produced by removing a foreground model from the 'unreduced' maps using the Foreground Template Model discussed in Hinshaw, et.al., 2006 and Page, et.al, 2006; see those papers for details. Briefly, synchrotron, free-free, and dust emission templates were modeled and then subtracted from the single year 'unreduced' maps. The goal was to produce a set of maps with the foreground removed while retaining WMAP's noise characteristics.

Because the K and Ka maps were used to produce the foreground models, only Q, V, and W band foreground reduced maps were created and delivered to LAMBDA.

As with the 'unreduced' maps, full three year maps were produced by performing a weighted, pixel-by-pixel, mean of the three single year maps; the N_Obs measurement was used to weight this mean. The N_Obs measurements were added together to produce the final, three year, N_Obs measurement.

The same foreground template model was used to produce foreground reduced high resolution (res 10) V and W maps.

WMAP maps are stored in FITS binary table extensions. The maps are stored in the first extension in a file; the format of this table depends upon whether polarization maps have been included in the file. Some files also contain the polarization covariance matrices for the maps; if supplied these matrices are stored in a second binary table extension.

As previously stated, the first FITS extension contains the maps. These maps are in a nested HEALPix format, with each row representing a single pixel. There are either four or two columns depending upon whether or not polarization maps are included; these columns are:

TEMPERATURE	The Stokes I, or temperature, measurement in mK (thermodynamic).
Q_POLARISATION	The Stokes Q polarization measurement in mK (thermodynamic).
U_POLARISATION	The Stokes U polarization measurement in mK (thermodynamic).
N_OBS	The effective number of observations.

The column names were selected to be compatible with existing HEALPix software. The TEMPERATURE and N_OBS columns are the only columns that exist in files that do not contain polarization maps.

Additional Information

• Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Beam Profiles, Data Processing, Radiometer Characterization and Systematic Error Limits, N. Jarosik, et.al. (2006)
• Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Temperature Analysis, G. Hinshaw, et.al. (2006)
• Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Polarization Analysis, L. Page, et.al. (2006)
• WMAP Three Year Explanatory Supplement

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