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II. The WISE All-Sky Data Products

1. General Properties of the All-Sky Data Release

The WISE All-Sky Data Release includes all the data taken from the time the scan mirror rate was correctly set until the time that the outer hydrogen tank that cooled the telescope ran out of hydrogen. During this period all four bands were operating in a very stable thermal environment. During the whole mission WISE scanned along lines of constant ecliptic longitude from near one ecliptic pole to near the other pole with a scan rate close to the orbital rate of 3.8 arc-minutes/second in order to always point away from the Earth. Each semi-circular track from ecliptic pole to ecliptic pole is called a scan. During each scan WISE took a frameset every 11 seconds. Each frameset contains 4 images, one for each band, with all bands observing the same 47 arc-minute square patch of sky. Images within each frameset were rejected and not included in the higher level data products if they were streaky due to spacecraft acceleration or if scattered Moon light was too strong, a problem that was worse at long wavelengths.

The highest level data products are the:

  1. co-added Image Atlas, which has been match filtered to maximize signal-to-noise, and
  2. a Catalog of over 563 million objects with signal-to-noise ratio greater than 5 in at least one WISE band.

Also provided is a Reject Table of objects that were detected on the image atlas tiles with signal-to-noise greater than 3.5, but rejected from the Catalog for reasons ranging from being a duplicated extraction in the Atlas Tile overlap regions, for being an identified image artifact, or for not reaching SNR 5 in any band.

The lower-level data products included in the release are the Single-exposure images (Level 1b) and a Database of all the object detections on the single frames. This database is very useful for variability studies. The Single-exposure images and object detection database include frames that were not used for making the higher level products, so all of the sky is covered by data in this release.

Last Updated: 2012 March 15

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