VII. 3-Band Cryo Data Release

3. 3-Band Cryo Data Processing

Science data processing for the WISE 3-Band Cryo survey phase was carried out using version 4.5 of the WISE Science Data System (WSDS). WSDS v4.5 was adapted from WSDS v4 which was used to process the full cryogenic survey data, and that produced the All-Sky Release data products. WSDS v4.5 maintains all of the major elements of the earlier version, and preserves all improvements and benefits that constitute WISE second-pass data processing.

The modifications that were made for WSDS v4.5 deal primarily with dropping W4 data from all aspects of the processing, and accommodating the changes to and time-dependence of the performance of the W1, W2 and W3 detectors. During the full cryogenic mission phase, the WISE payload was so stable that a single set of calibration image products and parameters could be used for the entire data set. 3-Band Cryo phase processing required developing the infrastructure for time-dependent calibrations and algorithms in many of the pipeline science modules.

Section VII.3.a contains a summary of the major pipeline changes that were made for 3-Band Cryo data processing. The basic design, functionality and algorithms for each WSDS pipeline science module are described in IV.4. Changes to the individual modules for WSDS v4.5 are described in more detail in sections VII.3.b-i. Modules that are not explicitly included within subsections in VII.3 are largely unchanged from WSDS v4.

a. Summary of Pipeline Modifications for 3-Band Cryo Processing

• Functionality that involves W4 data was removed from all science modules and pipeline wrappers.


• Infrastructure for handling time-dependent parameter file input for all science modules was introduced. This was generally handled by defining discrete calibration intervals during which calibration products and module parameters are fixed. Different modules utilized different intervals.


• Operating parameters for all modules were tuned for the characteristics of 3-Band Cryo data.


• New and time-dependent calibrations were developed and utilized in the Single-Exposure Image Calibration (VII.3.b), Position Reconstruction (VII.3.d), and Photometric Calibration (VII.3.g).


• Saturated pixel tagging was was recovered for bright point sources using prior knowledge of the position and flux from the All-Sky Catalog and external sources (see VII.3.b.iv.1).


• Parameters used to compute of the probability of flux variability were updated, and the computation in W3 was dropped because of the severe changes in sensitivity in that band during the 3-Band Cryo operations (VII.3.c.i).


• The Source Working Database that contains the deep source extractions from Multiframe Pipeline processing was not split into a separate Catalog and Reject Table in the Final Product Generation step.


• Positional associations with All-Sky Release Catalog sources were added to the 3-Band Cryo Source Working Database (VII.4.e).

Last Update: 2012 July 26