The Standard Product Generation (SPG) Pipeline (otherwise known as Off-Line Processing, OLP) processes the raw data telemetered down from ISO (in terms of microvolts, scanner positions etc) into more conventional astronomical units of flux against wavelength. This chapter describes the Standard Product Generation Pipeline, the error propagation through it and any side-effects noted on the processed data.
The SPG pipeline is composed of three parts:
Extracting from the raw data stream the instrument data and placing
it 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, the relationship between voltages per second and fluxes, etc.
Examples of the data produced by these steps are given throughout this manual. Sections 4.2 to 4.5 show ERD, SPD and AAR examples for each AOT. Sections 4.6.2, 4.6.1 and 5.8 give examples of short stretches of observations to highlight certain features.