NICMOS Instrument Handbook for Cycle 11

On-The-Fly-Reprocessing (OTFR)

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Each HST observation consist of several packets of data which are time-tagged on the spacecraft, sent to the ground by a Tracking and Data Relay Satellite (TDRS) link to Goddard Space Flight Center (GSFC), and sorted by the PACket processOR (PACOR) at GSFC into a packetized data set called a "POD" file (Packetized Observation Data). The individual POD files are sent by PACOR-A to the Operational Processing and Uplink System (OPUS) at STScI where the data are processed (translates data from telemetry to FITS files), calibrated, and Archived.

"On-The-Fly-Reprocessing" (OTFR) is a software interface to the HST Archive that regenerates the "raw" (uncalibrated) science data from the POD files and provides the most up-to-date calibration of the data possible to the Archive user. Since OTFR starts with the POD files, any changes to header keywords, or the addition of keywords, are automatically performed. The OTFR system will use the best available calibration reference files and the most recent versions of the OPUS processing pipeline and calibration software (calnica & calnicb). OTFR is transparent to the Archive user. Removing pedestal during pipeline calibration is under investigation and maybe implemented in the future. The release of OTFR for STIS and WFPC2 occurred in May 2001. OTFR for NICMOS is planned for the later part of 2001.