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WMAP

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

Product Name
I Maps (per frequency)
Mission
WMAP
Coord. System
Galactic
Projection Type
HEALPix, nested, res 9 (Nside=512)
Resolution
0.23°- 0.93° (frequency dependent)

Description

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

K

Ka

Q

V

W

sigma_0 (mK)

1.42366

1.44883

2.21122

3.11236

6.49760

More details can be found in:

WMAP Explanatory Supplement

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Goddard Space Flight Center, National Aeronautics and Space Administration
HEASARC Director: Dr. Alan P. Smale
LAMBDA Director: Dr. Eric R. Switzer
NASA Official: Dr. Eric R. Switzer
Web Curator: Mr. Michael R. Greason