Data Processing

 

The scientific data are contained in the satellite telemetry and examined in real-time during operations by two processes. Real Time Engineering Assessment, RTA, monitors instrument health and proper command execution. Quick Look Scientific Assessment, QLA, provides an initial indication of the success or failure of an observation.

To produce a set of standard products from each observation, all data is passed through a process which runs off-line. The goal of the pipeline processing is to provide observers with data from which they can work without having to know details of specific features of the ISO instruments and spacecraft. The observers themselves are responsible for the scientific analysis and interpretation of their data.

The following information is forwarded to the observer in FITS format:

1. Edited Raw Data (ERD). This low level data product - essentially reformatted telemetry - contains raw instrument data.
2. Standard Processed Data (SPD). This is the data product from which most observers are expected to work. Its derivation involves a certain amount of calibration and removal of instrument-specific peculiarities. SPD is intended to be a self-contained product, offering high flexibility in data analysis at the observer's home institute without requiring a full understanding of instrument-specific features.
3. Auto Analysis Results (AAR): This product will, generally, contain final calibrated data, generated in an automatic process, which will give an indication of what will be found when observers perform their own detailed analysis of the Standard Processed Data.

The actual status of data products and their validation can be found under

 http://isowww.estec.esa.nl/obs_stat/curr_stat.html.

Positional information is provided in the FITS header of the product. The commanded position is always present in the header while an improved position is added to the header of SPD and AAR.

Observers are expected to have software packages for data reduction at hand at their home institutes.

The data products, together with appropriate calibration and auxiliary files are being distributed on CD-ROMs to the Principal Investigator of the proposal on a nominal timescale of a few weeks. Whenever possible, multiple observations for the same Principal Investigator will be combined on one CD-ROM.

In addition to the three data products mentioned above, auxiliary data will be made available to observers, such as calibration files and any other data that may be necessary for further processing of the products. All information on the data products is contained in the ISO Data User's Manuals (IDUMs), one for each instrument and one general description for the ISO spacecraft data. The latest version of these can be obtained via ftp from:

ftp.estec.esa.nl

under

pub/iso/doc/iso/idum