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16.1 Pipeline Processing

 Shortly after your data arrive at STScI they pass through the OPUS pipeline which processes and calibrates them. All of the steps performed by the pipeline are recorded in the trailer file for your dataset (*_trl.fits). The main steps performed by the pipeline are:

  1. The data are partitioned (separated into individual files, e.g., -engineering and science data are separated).
  2. The data are edited, if necessary, to insert fill in place of missing data.
  3. The data are evaluated to determine discrepancies between the subset of the planned and executed observational parameters.
  4. A list of calibration reference files to be used in the calibration of the data is created based on the executed observational parameters. This step does not generate comments in the NICMOS trailer file.
  5. The data are converted to a generic (FITS) format and the header keyword values are populated (known as generic conversion).
  6. The data are calibrated using a standard set of NICMOS calibration algorithms (calnica and calnicb). The calibration software used by the pipeline (step 6 above) is exactly the same as that provided within STSDAS (see below). The calibration files and tables used are taken from the Calibration Data Base System (CDBS) at STScI and are the most up-to-date calibration files appropriate for the instrument configuration used in the observation.


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