A science pipeline can be roughly described as a sequence of six basic steps which range from telemetry unpacking to database dredging to data formatting. But that's not the whole task. Most of the work, and most of the code in such a system is designed to handle the abnormal case. The OPUS applications which process a telemetry stream into standard FITS files fall into the following six components. Its function is to scan the incoming telemetry for known patterns and to segment the telemetry stream into its basic constituents.
Chunks can be of different sizes and types.
Packets of different types, which can arrive in any order, are segmented and put into their own files. This is a much more important issue when dealing with images and spectra than with time-tagged photon events. Data which has an implicit order rather than an explicit time-tag order is susceptible to misinterpretation if whole segments are out of order. This information describes the configuration of the instrument, the timing of the exposure, and the existence of associated exposures. It also controls the downstream calibration-that is, all calibration steps beyond the OPUS Generic Conversion determine the parameters of the science exposure from these keywords.