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In CUBISM, which calibration set should be used with which SSC IRS pipeline version?
Posted by z-Vandana Desai on 09 December 2008 10:51 AM
In order to understand the answer to this question, you need a little background on the SSC pipeline. Roughly every six months, the pipeline number (the "S-number") for all new Spitzer data (from all instruments) in the archive is incremented as a new software system is brought online at the SSC. Newly observed data will appear in the archive with a different S-number than older data. Parallel to the changes in the SSC pipeline, the IRS pipeline in particular may be improved. When pipeline changes include substantial improvements in IRS calibration or data quality, all past IRS campaigns will be reprocessed with the newest pipeline. If the IRS pipeline changes are very small, past campaigns will not be reprocessed. For this reason, users that have already downloaded data may not need to download it again when a new pipeline version is released. The decision to reprocess is made on a module-by-module basis. Thus, the pipeline version you find in the archive for LH may be different than the version you find for SL. Interested users may wish to visit the IRS pipeline history log in the IRS Instrument Handbook for a summary of what has changed with each new IRS pipeline version.

As of this writing (March 2011), all data in the IRS archive have been reprocessed with version S18.18 of the IRS pipeline.

CUBISM version 1.8 defaults to a calibration set corresponding to pipeline version S18.18.

If you downloaded your data and built cubes some time ago with an older version of CUBISM, then the calibration set you used is saved in the CUBISM cpj file. Therefore, you are free to use CUBISM version 1.8 in order to access its new features without compromising your calibration. However, you should check the IRS pipeline history log in the IRS Instrument Handbook to see if there have been changes which could affect your science. In that case, you should download your newly-processed data from the archive and use the default calibration in CUBISM version 1.8 .