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VIII. Post-Cryo Data Release


1. Introduction

b. Executive Summary of Post-Cryo Data Products


Contents

  1. Post-Cryo Release Products
    1. Single-Exposure Images
    2. Single-Exposure Source Database
    3. Known Solar System Object Possible Association List
  2. Preliminary Post-Cryo Release Products
    1. Single-Exposure Images
    2. Single-Exposure Source Database
    3. Known Solar System Object Possible Association List

i. Post-Cryo Release Products

WISE Post-Cryo Data Release Contents
ProductNumber of Entries
1. Single-Exposure Images901,271 image sets
2. Single-Exposure Source Database7,337,642,955 detections
3. Known Solar System Object Possible Association List4,699,277 entries corresponding to 290,164 asteroids, comets, planets and planetary satellites

1. Single-Exposure Images

The WISE Post-Cryo Release Single-Exposure images consist of 901,271 photometrically and astrometrically calibrated 1016x1016 pix at 2.75"/pix FITS image sets for each individual WISE exposure taken between 29 September 2010 and 1 February 2011. Each image set consists of:

The Post-Cryo Single-Exposure Images were produced during second-pass data processing and supersede the Post-Cryo Preliminary Data Release Products.

The 2013 Post-Cryo release has three fewer image sets that the Preliminary Post-Cryo release. The framesets corresponding to these image sets did not complete processing during the second-pass. One of these, scan/frame number 09866a144, failed in position reconstruction because it is badly streaked due to spacecraft motion. The other two framesets, 09918a195 and 10196a265, did not have W1 images downlinked. Data from both bands were required to be present in second-pass processing.

A general descriptions of the Single-Exposure Image sets are presented in VIII.2.b. Directions for accessing the Single-Exposure Image products are given in VIII.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 VIII.3.b.

Individual Single-exposure images are made available regardless of their quality. Users are strongly encouraged to read the Cautionary Notes for the Single-Exposure Images.

2. Single-Exposure Source Database

The WISE Post-Cryo Release Single-exposure Source Database is a compendium of position and flux information for 7,337,642,955 "sources" detected on the individual WISE 7.7s W1 and W2 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 Post-Cryo Single-Exposure Source Database was produced during second-pass data processing and supersedes the Post-Cryo Preliminary Release Single-Exposure Source Database.

The 2013 Post-Cryo Release Single-exposure Source Database contains a factor of 1.5 more entries than the Preliminary Release Source Database. The increase arises primarily because a lower source detection SNR threshold was used during second-pass processing than during the first-pass (3.0 vs. 4.0). Improved image calibrations also reduced the noise in the images, which effectively improved the sensitivity leading to more source extractions.

The general properties and detailed column descriptions of the Single-Exposure Source Database are presented in VIII.2.a. Access instructions for the Single-Exposure Source Database are given in VIII.1.c. Descriptions 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 VIII.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 should be used with caution. Users are strongly encouraged to read the Cautionary Notes before using the Database.


3. Known Solar System Object Possible Association List

The Post-Cryo Release Known Solar System Object Possible Association List contains 4,699,277 entries that correspond to 290,164 asteroids, comets, planets and planetary satellites with orbits known at the time of WISE second-pass data processing, that were predicted to be within the field-of-view at the time of individual WISE exposures. These are significantly larger than the numbers in the Preliminary Post-Cryo Release Known Solar System Object Possible Association List because the number of known objects increased between the time of the first- and second-pass processing of the NEOWISE Post-Cryo data.

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 detected on a WISE Single-exposure, 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. Users are strongly encouraged to read the Cautionary Notes to understand the limitations of the Known Solar System Object Possible Association List.

The column descriptions for the Known Solar System Object Association table are given in VIII.2.e, and a description of the processing algorithms used to predict the positions of known solar system objects is given in IV.4.e. Directions for accessing the Known Solar System Possible Association table are given in VIII.1.c.


ii. Post-Cryo Preliminary Release Products

The Post-Cryo Preliminary Release data products were produced during first-pass data processing during WISE on-orbit operations, as input for the WISE Moving Object Pipeline. The Preliminary Release products are superseded by the Post-Cryo Release products that were generated from a complete reprocessing using improved calibrations and data reduction algorithms..

WISE Post-Cryo Preliminary Data Release Contents
ProductNumber of Entries
1. Single-Exposure Images901,274 image sets
2. Single-Exposure Source Database4,913,391,616 detections
3. Known Solar System Object Possible Association List4,150,398 entries corresponding to 257,189 asteroids, comets, planets and planetary satellites

1. Single-Exposure Images

The WISE Post-Cryo Preliminary Release Single-Exposure images consist of 901,274 photometrically and astrometrically calibrated 1016x1016 pix at 2.75"/pix FITS image sets for each individual WISE exposure taken between 29 September and 1 February 2011. Each image set consists of:

A general descriptions of the Preliminary Release Single-Exposure Image sets are presented in VIII.2.b. Directions for accessing the images are given in VIII.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 VIII.3.b.

Individual Single-exposure images are made available regardless of their quality. Users are strongly encouraged to read the Cautionary Notes for the Single-Exposure Images.

2. Single-Exposure Source Database

The WISE Post-Cryo Preliminary Release Single-exposure Source Database is a compendium of position and flux information for 4,913,391,616 "sources" detected on the individual WISE 7.7s W1 and W2 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 general properties and detailed column descriptions of the Single-Exposure Source Database are presented in VIII.2.a. Access instructions for the Single-Exposure Source Database are given in VIII.1.c. Descriptions 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 VIII.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 should be used with caution. Users are strongly encouraged to read the Cautionary Notes before using the Database.

3. Known Solar System Object Possible Association List

The Post-Cryo Preliminary Release Known Solar System Object Possible Association List contains 4,150,398 entries that correspond to 257,189 asteroids, comets, planets and planetary satellites with orbits known at the time of WISE first-pass data processing, that were predicted to be within the field-of-view at the time of individual WISE exposures. 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 detected on a WISE Single-exposure, 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. Users are strongly encouraged to read the Cautionary Notes to understand the limitations of the Known Solar System Object Possible Association List.

The column descriptions for the Known Solar System Object Association table are given in VIII.2.e, and a description of the processing algorithms used to predict the positions of known solar system objects is given in IV.4.e. Directions for accessing the Known Solar System Possible Association table are given in VIII.1.c.


Last update: 2017 June 9


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