WMAP DR1 I Maps (per frequency)

The data made available through this page has been updated. The most recent version of this data may be accessed through https://lambda.gsfc.nasa.gov/product/wmap/current/

Coordinate System:
Projection Type:
0.23° - 0.93° (frequency dependent)
HEALPix, nested, res 9 (Nside=512)
Download Links:

Five maps, one for each of the five frequency bandpasses observed by WMAP. These frequency maps are derived from the individual differencing assembly maps.

For each pixel in a frequency map, noise weighting is used to compute the average temperature from the individual differencing assembly map values. Since there is only one differencing assembly for the K and Ka bandpasses, the K and Ka frequency maps are identical to the K1 and Ka1 differencing assembly maps. The Q map is the noise-weighted result from combining Q1 and Q2, V is derived from V1 and V2, and W derives from W1, W2, W3 and W4.

The data provided in each frequency map consist of two fields for each pixel:

  • the thermodynamic temperature, in mK, and
  • the effective number of observations, N_obs.

Pixel noise can be evaluated from N_obs via sigma = sigma_0/sqrt(N_obs), where sigma_0 for each frequency is listed in the following table:

Frequency band






sigma_0 (mK)






More details can be found in:

WMAP Explanatory Supplement

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