WMAP Angular Resolution

CMB anisotropy information from current and proposed high resolution (< 0.3°) measurements over limited sky regions will likely succeed from ground and balloon-based platforms. The priority for the WMAP space mission is to map the entire sky with > 0.3° angular resolution where the cosmological return is high, and the data cannot be readily obtained in any other way. The WMAP optics feature back to back 1.4 m x 1.6 m primary reflectors which lead to an angular resolution of < 0.25° in the highest frequency (90 GHz) channel.

The following table gives the angular resolution to be obtained from each of the five WMAP frequency bands. The value quoted is the full width at half maximum (FWHM) of the approximately gaussian central beam lobe, in degrees. The definitive measurements of the main beam properties will be obtained from observations of the planet Jupiter in flight. This information will be used to compute the effective beam response on the sky after accounting for the azimuthal averaging that occurs from observing a given sky pixel with a range of beam orientations. This complete information will be made available with the sky map data when it is processed.