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41.1 Pipeline Calibration

The HSP pipeline reduction was not used extensively by the HSP team, for a number of reasons. For example, many datasets are too large for IRAF and the ground system simply could not produce a FITS file. Some HSP data were taken at such high speeds that the time series consist of a few ones separated by large runs of zeroes, making the deadtime corrections and dark count subtraction inappropriate. Other calibrations, such as absolute timing of data samples, required working with fundamental data such as daily spacecraft clock calibrations which were not available to the pipeline as quickly as needed.

For these and other reasons, most HSP datasets were reduced in-house at the University of Wisconsin when needed. The following description of the pipeline will give the user an introduction on how raw data are converted into calibrated data.

HSP data are received in the raw and calibrated format. The STSDAS calhsp task can be run to recalibrate the raw HSP data. calhsp takes the raw GEIS files containing counts in the digital data and digital numbers in the analog data and converts the data to calibrated data containing counts per second for point source and counts per second per square arcsecond for extended source data. All of the various data formats get calibrated, except for area scan data.

The calhsp task performs the following basic calibration processing steps (note that the sequence differs somewhat depending on the data type, see the flowchart on the next page):

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