Some FORS1 calibration data are presently monitored to extract information about their quality and the instrument performance. The quality information is extracted into so-called QC parameters.

FORS1 calibration data are pipeline-processed to create calibration products. The quality of the products is measured by QC1 parameters. Most QC1 parameters are obtained by pipeline procedures; some are measured by post-pipeline recipes.

All measured QC1 parameters are stored in a database. Their evolution with time is evaluated by the trending process.

The following properties of FORS1 detector and instrument components are trended:

• bias level and read noise
• detector parameters
• dark current

zeropoints and image quality

• zeropoints per frame and per night
• image quality
• extinction coefficients and colour terms

wavelength calibrations

• LSS
  
• MOS