The XMM-Newton Science Analysis System (SAS) for the X-ray instruments can be broadly described as a two-stage process (each of these stages eventually sub-divided into further sub-processes). The first one (called ``reduction'' hereinafter) produces calibrated concatenated event lists from the uncalibrated chip-based event lists that are included in the ODF/SDF. To perform this task, the SAS makes use of the information contained in the auxiliary and housekeeping files, as well as the calibration algorithm/files, which constitute the CCF. In this context, calibrated means that the raw quantities, which characterise the detection of each photon by the X-ray detectors are converted to physical quantities (or quantities which can be equivocally mapped into physical quantities); concatenated means that a single event file is produced, containing photons detected by different chips of the same detector from different exposures, provided that the experimental configurations are mutually consistent. Event lists corresponding to different detectors (e.g.: MOS1 and MOS2) are not concatenated. The second stage is the extraction of scientific products (images, light curves, spectra, sub-event lists selected according to different scientific and/or instrumental criteria) from the calibrated concatenated event lists.
Given the above structure, the calibrated concatenated event lists (simply ``event lists'' hereinafter) play a fundamental role in the scientific analysis of XMM-Newton data. The event lists are the starting point of the analysis and interpretation of XMM-Newton data.
This Section deals with a short description of the structure of the event files, which are produced by the SAS reduction tasks (epproc, emproc, rgsproc meta-tasks) for EPIC and RGS scientific modes. ``Diagnostic'' or ``engineering'' modes produce direct images and can therefore not be encompassed in the above scheme. Calibrated and concatenated event lists are also delivered as PPS products. The detailed format of such event lists can differ slightly from that of the files produced by the epproc, emproc, and rgsproc meta-tasks. A detailed description of the PPS-generated calibrated concatenated event lists is given by . In Sect. 8 a summary of all PPS products is given. For the OM, events files are only produced for the fast mode by the SAS task omfchain. The OM fast mode event file is an intermediate product and is not delivered with the pipeline.
Event timing is provided as seconds elapsed since the mission reference time. See Appendix A for more details.