Detector Monitoring as part of VLT Science and Data Flow Operations

The ESO Paranal observatory is operating a heterogeneous set of science detectors. The maintenance and quality control of science detectors is an important routine task to retain the technical and science performance of the instrumentation. In 2006 a detector monitoring working group was built devoted with the following tasks: inventory of the currently existing detector calibration plans and monitored quality characteristics, completion and homogenization of the detector calibrations plans, design and implementation of cross-instrument applicable templates and data reduction pipeline recipes and monitoring tools. The instrument calibration plans include monthly and daily scheduled detector calibrations. The monthly calibrations are to measure linearity, contamination and gain including the inter-pixel capacitance correction factor. A reference recipe has been defined to be applicable to all operational VLT instruments and has been tested on archive calibration frames for optical, near- and mid-infrared science detectors. The daily calibrations measure BIAS or DARK level and read-out noise in different ways. This has until now prevented cross detector comparison of performance values. The upgrade of the daily detector calibration plan consists of the homogenization of the measurement method in the existing pipeline recipes.