This chapter describes the Standard Product Generation Pipeline , which converts the raw data telemetered from ISO into useful scientific data. It describes all the stages of the pipeline, the error propagation through it and any side-effects noted on the processed data.
The pipeline is composed of three parts:
Extracting the instrument data from the raw data stream into Edited
Raw Data (ERD ) files. This process is a reformatting only and will
not be discussed further.
ERD to Standard Processed Data (SPD ) stage, known as
Derive-SPD . This involves removing all instrumental effects
on timescales of less than 1 reset interval, converting detector readouts
(voltages against time) into slopes and assigning, where possible,
wavelengths with detectors.
SPD to Auto-Analysis Results (AAR ) stage, known as
Auto-Analysis . This further process the SPD removing
instrumental effects on timescales of greater than 1 reset interval and
converts slopes to fluxes.
In the course of Derive-SPD and Auto-Analysis several files are used that describe the behaviour of the instrument and its performance. These files are known, for historical reasons, as Cal-G files. They contain such things as the conversion between scanner position and wavelength, voltages per second and fluxes, the separation between the three apertures etc.