Quality Control

 

Quality Control provides the tools necessary for the calibration of the VLT instruments and the assessment of the data quality. For this purpose the system includes:

• the Calibration Plan maintained by the Instrument Scientist and describing the rules and recipes, calibration and physical data, as well as instrument descriptions, necessary for a given instrument.
• the Calibration Server, a local database structure storing all the above products. Applications allow to verify the data stored in the calibration server and submit them to the central archive.
• Instrument Models, ranging from ETCs to imaging simulations allowing to predict and control instrument performance.

The main activity of Quality Control is to monitor the performance of the pipeline and to assess the data quality. To this end the following systems are regularly monitored:

• Pipeline
  • Detector and calibration units
  • Observation conditions (e.g. sky background)
  • Instrument function testing: focus, instrument response
• Instrument
  • Specific testing: scattered light, non-linearities
  • Comparisons to instrument models
  • Certification of the master calibration data
• Observatory
  • Cross-correlations
  • Trend analysis

Number of the above tasks will be implemented in the Quality Control pipeline and be executed during observations. Another part will be available in the form of interactive procedures for use by the DFIR. If a problem is identified which relates to the instrument, the DFIR will make use of a central problem report system.

An aspect of the Quality Control will be the production and maintenance of instrument models for the purpose of exposure time calculation and control of the instrument efficiency.