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I. Introduction

I.3. Executive Summary of the AllWISE Data Products

AllWISE Data Release Contents
Primary ProductsNumber of Entries
a. AllWISE Source Catalog747,634,026 objects
b. AllWISE Multiepoch Photometry Database42,759,337,365 measurements
c. AllWISE Image Atlas18,240 image sets
Ancillary ProductsNumber of Entries
d. AllWISE Reject Table428,787,253 detections
e. Full-Depth Ecliptic Polar Atlas Images73 image sets

I.3.a. AllWISE Source Catalog

The AllWISE Source Catalog contains astrometry and photometry for 747,634,026 objects detected on the deep AllWISE Atlas Intensity Images. Positions, magnitudes, astrometric and photometric uncertainties, flags indicating the reliability and quality of the source characterizations, and associations with the 2MASS Point and Extended Source Catalog sources are presented for each source. New to the AllWISE Source Catalog are measurements of the apparent motion of each source that exploit the two independent WISE sky coverage epochs.

The AllWISE Source Catalog is superior to the WISE All-Sky Release Catalog and should be your primary reference for discrete objects in the mid-IR sky, with the one exception described below. The AllWISE Catalog sensitivity is better in the W1 and W2 bands because of increased depth-of-coverage provided by the coaddition of data from the 4-Band, 3-Band and Post-Cryo survey phases. The photometric accuracy in all four bands is improved because faint source flux biases have been corrected and background estimation has been made more robust. Astrometry accuracy is better because of the correction for the proper motion of 2MASS astrometric reference stars in the 11 years between the two surveys, and the incorporation of the multiple independent source measurements in the image overlap regions into the astrometric solutions. Measurements of the apparent motion of sources are provided for the first time, and improved source flux variability metrics have been computed.

The WISE All-Sky Source Catalog provides better photometry for sources brighter than the saturation limit in bands W1 and W2, W1<8 mag and W2<7 mag, that were observed during the Post-Cryo survey phase. Saturated source photometry during the Post-Cryo phase is systematically biased with the respect to that in the other phases, when they were combined in for AllWISE the resulting measurements have larger net uncertainties. The All-Sky Catalog that is limited to data from the 4-Band Cryo phase does not suffer from this bias.

The general properties and column descriptions of the Source Catalog are presented in II.1. Instructions for accessing the Catalog are given in I.5. Production of the AllWISE Source Catalog is described in V.1. Users are strongly encouraged to read the Cautionary Notes to make optimal use of the Catalog in their research.

I.3.b. Multiepoch Photometry Database

The AllWISE Multiepoch Photometry (MEP) Database is a compendium of 42,759,337,365 time-tagged, photometric measurements of all of the deep source detections in the Source Catalog and Reject Table made on the Single-exposure images. The profile-fit photometry on the Single-exposures is forced at the location of the deep source detection, so each Catalog/Reject Table entry has a corresponding group of entries in the Multiepoch Source Database.

The MEP Database is not a traditional catalog of discrete objects that is can be used for statistical population and discovery investigations. It is a resource to obtain follow-up light curves and flux measurement history for sources that are found in the AllWISE Source Catalog or Reject Table. Entries in the Catalog and Reject Table are cross-referenced to those in the MEP Database by unique identifiers and source position.

While the AllWISE MEP Database and the All-Sky, 3-Band Cryo, and NEOWISE Post-Cryo Release Single-exposure Source Working Databases all contain flux measurements made on the individual Single-exposure images, the MEP and the Single-exposure Databases are different in a number of important ways. The MEP Database contains the measurements of all deep detections from the Catalog and Reject Table on the individual images, while the Single-exposure DBs are limited to sources that are bright enough to have been detected on the Single-exposures. The measurements in the MEP Database also benefit from the improved AllWISE photometry algorithms and calibrations that correct deficiencies in the earlier data processing. See III.1.b for additional differences between the MEP and Single-exposure Databases.

The general properties and column descriptions of the MEP are presented in III.1. Instructions for accessing measurements in the MEP Database are given in I.5. Tips on how to make the best use of the MEP Database are given in III.1.c. A description of how the MEP Database was generated can be found in V.3.b.v.

Users are strongly encouraged to read the Cautionary Notes to make optimal use of the Database in their research.

I.3.c. AllWISE Image Atlas

The AllWISE Image Atlas is comprised of 18,240 4095x4095 pix at 1.375"/pix FITS format image sets. Each image set consists of:

The AllWISE Image Atlas supersedes the Atlases from the WISE All-Sky and 3-Band Cryo Releases. The AllWISE Atlas benefits from the recalibration of the 4-Band and 3-Band Cryo Single-exopsure image pixels and the improvements to the Single-exposure image WCS information in all survey phases that were performed for AllWISE processing. Another key improvement is that lower coverage regions in W1 and W2 in All-Sky Release Atlas Images are "filled-in" because of the addition of Single-exposure images from all survey phases.

A general description of the format and properties of the AllWISE Atlas Image sets is presented in IV.1. Access instructions for the AllWISE Atlas Images are given in I.5. The AllWISE Atlas Image products were generated using similar algorithms used to produce the All-Sky Release Atlas Image sets, with improvements and updates that are described in V.3.a.

Please read the Cautionary Notes for the Atlas Images.

See also the Full-depth Ecliptic Polar Atlas Images.

I.3.d. AllWISE Reject Table

The AllWISE Reject Table contains measurements of 428,787,253 detections made on the Atlas Images that were not included in the Source Catalog because they did not satisfy the Catalog source selection criteria. These extractions were rejected from the Catalog because they are fainter than the Catalog's SNR requirements, duplicate extractions of sources in the Catalog, or they are believed to be detections of image artifacts.

The Reject Table format is the same as that for the AllWISE Source Catalog, with the exception that the Reject Table contains one additional column that allows you to identify entries that may be duplicate, redundant extractions of Catalog sources. The content and format of the Reject Table is described in II.1.a. Directions for accessing the Reject Table are given in I.5. The data processing steps and algorithms used to produce the source extractions in the Reject Table are the same as used to generate the Enhanced Source Catalog, described in V.1.

The Reject Table is not a well-vetted list of reliable mid-infrared source detections like the Source Catalog. Your first assumption should be that all entries in the Reject Table are either duplicates of entries in the Catalog, or spurious detections. However, the Reject Table does contain low SNR extractions of real sources below the Catalog's limits, as well as reliable, higher SNR extractions that were omitted from the Source Catalog because of over-aggressive artifact flagging in regions such as the ecliptic poles and high density fields in the Galactic plane. Used with caution, the Reject Table can be a useful database that augments the Source Catalog when looking for sources that appear on the Atlas Images but are not found in the Catalog.

Users are strongly encouraged to read the Cautionary Notes before using the Reject Table.

I.3.e. Full-Depth Ecliptic Polar Atlas Images

The AllWISE Full-depth Ecliptic Polar Atlas Images consist of 73 special Atlas Image sets that were generated for Tiles near the Ecliptic poles whose frameset-coverage was artificially attenuated to approximately 160 frameset depth during the AllWISE Multiframe processing. The Full-depth Atlas Images were constructed using all framesets that meet basic quality criteria without coverage attenuation. The additional depth is most apparent in the appearance of the W3 and W4 Full-depth Images when compared with the attenuated coverage Atlas Images. The confusion limits is reached even in the attenuated coverage W1 and W2 Atlas Images, so the additional depth-of-coverage in the Full-depth images does not result in a significant gain in the sensitivity over the attenuated Atlas Images.

There is no corresponding Source Catalog or Reject Table from the Full-depth Polar Atlas Images.

The Full-Depth Polar Atlas Image set were constructed the same way as the AllWISE Atlas Images, except that many more framesets were coadded. Access to the Full-depth Atlas Image sets is available in IV.5.

Please read the Cautionary Notes for the AllWISE Atlas Images.

Last update: 22 November 2013

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