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VII. 3-Band Cryo Data Release


1. Introduction

b. Executive Summary of 3-Band Cryo Data Products


WISE 3-Band Cryo Data Release Contents
ProductNumber of Entries
i. Image Atlas5,649 image sets
ii. Source WDB261,418,479 detections
iii. Single-Exposure Images392,879 image sets
iv. Single-Exposure Source Database3,703,319,374 detections
v. Known Solar System Object Possible Association List1,800,976 entries corresponding to 106,573 asteroids, comets, planets and planetary satellites

i. Image Atlas

The WISE 3-Band Cryo Image Atlas is comprised of 5,649 4095x4095 pix at 1.375"/pix FITS format image sets. Each image set consists of:

The general properties and descriptions of the Atlas Image sets are presented in VII.2.b.i. Access instructions for the WISE 3-Band Atlas Images are given in VII.1.c. The algorithms used to produce the Atlas Image products and how they differ from those used to generate the All-Sky Release Atlas Images are described in VII.3.e.

Users are strongly encouraged to read the Cautionary Notes for the Atlas Images, and to view the gallery of anomalies and features known to exist in the Images.

ii. Source Working Database

The WISE 3-Band Cryo Source Working Database (WDB) contains astrometry and photometry for 261,418,479 objects detected on the Atlas Intensity Images. Positions, magnitudes, astrometric and photometric uncertainties, flags indicating the reliability and quality of the source characterizations, and associations with the WISE All-Sky Release Catalog and the 2MASS Point and Extended Source Catalog sources are presented for each source.

The 3-Band Cryo WDB is not a well-vetted list of reliable mid-infrared source detections like the WISE All-Sky Release Catalog. The 3-Band Cryo WDB entries include both detections of real astrophysical sources, along with low SNR noise excursions, spurious detections of image artifacts and transient pixel events, and duplicate, redundant entries of source detections in Atlas Tile overlap regions.

The 3-Band Cryo WDB is best used as a resource to learn more about objects that are found in the WISE All-Sky Release Source Catalog. Because the 3-Band Cryo observations are independent measurements of sources in approximately 30% of the sky, the WDB provides information about potential proper motions and flux variability of All-Sky Catalog sources. The reliability of a faint source from the All-Sky Catalog can be verified if it appears in the 3-Band Cryo WDB, particularly for those with detections in W1 and W2 where the sensitivity is close to the full-cryo mission phase. Finally, the 3-Band WDB provides potential source information for regions with low or even no-coverage in the All-Sky Catalog.

The general properties and column descriptions of the Source WDB are presented in VII.2.a. Instructions for accessing the Catalog are given in VII.1.c. A description of the data reduction algorithms used to generate the the Source WDB and differences from those used to generate the All-Sky Catalog can be found in VII.3. Users are strongly encouraged to read the Cautionary Notes to make optimal use of the WDB in their research.

iii. Single-Exposure Images

The WISE 3-Band Cryo Release Single-Exposure images consist of 392,879 photometrically and astrometrically calibrated 1016x1016 pix at 2.75"/pix FITS image sets for each individual WISE exposure taken between 6 August and 29 September 2010. Each image set consists of:

The Single-Exposure Images were produced during data processing for the main WISE mission, as input for the WISE Moving Object Pipeline, and for the generation and quality assessment of the Atlas Image and Source WDB.

The properties and descriptions of the Single-Exposure Image sets are presented in VII.2.d. Directions for accessing the Single-Exposure Image products are given in VII.1.c. The processing method and algorithms used to produce the Single-Exposure images and how they differ from those used for the full cryogenic mission phase images are described in VII.3.b.

Individual exposure images are made available even if they were of insufficient quality to be used in the construction of the coadded Image Atlas. Users are strongly encouraged to read the Cautionary Notes for the Single-Exposure Images, and to view the gallery of anomalies known to exist in the Images.

iv. Single-Exposure Source Database

The WISE 3-Band Cryo Single-exposure Source Database is a compendium of position and flux information for 3,703,319,374 "sources" detected on the individual WISE 7.7 sec (W1 and W2) and 8.8s/4.4s/2.2s/1.1 sec (W3) Single-exposure images. Because WISE scanned the same region of the sky multiple times, the Single-exposure Database contains multiple, independent measurements of objects on the sky. Positions, magnitudes in the four WISE bands, astrometric and photometric uncertainties, flags indicating measurement quality, the time of observations and associations with the 2MASS Point Source Catalog are presented for entries in the Database.

The Single-Exposure Source Database was produced as input for as input for the WISE Moving Object Pipeline, and for the generation and quality assessment of the Atlas Image and Source WDB.

Detailed column descriptions of the Single-Exposure Source Database are presented in VII.2.c. Access instructions for the Single-Exposure Source Database are given in VII.1.c. A detailed description of the source detection and photometry algorithms used to generate the Single-exposure Database and how they differ from those used to generate the Single-exposure Database from the full-cryogenic mission phase can be found in VII.3.

Entries in the Single-exposure Database include detections of real astrophysical objects, as well as spurious extractions of low SNR noise excursions, transient events such as cosmic ray strikes and noisy pixels, and artifacts and scattered light from bright sources including the moon. Many unreliable detections are flagged in the Single-exposure Database, but the Database must be used with caution. Users are strongly encouraged to read the Cautionary Notes before using the Database.

v. Known Solar System Object Possible Association List

The 3-Band Cryo Known Solar System Object Possible Association List contains 1,800,976 entries that correspond to 106,573 asteroids and comets with orbits known at the time of the WISE 3-Band Cryo second-pass data processing, that were predicted to be within the field-of-view at the time of individual WISE exposures. No planets or planetary satellites were observed during the 3-Band Cryo mission phase. The positions of individual objects were observed multiple times, so most have multiple entries in the list. When the predicted position of a solar system object is in proximity to a source detection in the WISE Single-exposures, the WISE source position and brightness information are also provided.

The purpose of the Known Solar System Object Possible Association List is to advise users if a Single-exposure Source Database entry may be confused with or contaminated by a foreground solar system object. The List is not a vetted list of solar system object identifications. For a reliable, well-vetted list of WISE solar system object detections, please use the Moving Object Tracklets that are accessible via the Minor Planet Center. The 3-Band Cryo Known Solar System Object Possible Association List has the same characteristics and limitations as the list in the All-Sky Data Release. Therefore, you are strongly encouraged to read the Cautionary Notes to the All-Sky Release Known Solar System Object Possible Association List.

The column descriptions for the Known Solar System Object Association table are given in VII.2.j. The processing algorithms used to predict the positions of known solar system objects is the same as used for the WISE All-Sky Data Release, and is described in given in IV.4.e. Directions for accessing the Known Solar System Possible Association table are given in VII.1.c.


Last update: 2012 July 26


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