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Quality Control

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Trending & QC1
general info
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The Quality Control Group in Garching provides quality checks of the ISAAC data. These checks are part of the Quality Control (QC) process. They are executed on raw data as well as on pipeline-processed data.

The QC checks consist of

  • Quality Control Level 0 (QC0),
  • Quality Control Level 1 (QC1),
  • trending.


QC0 involves checks whether the user-defined observational constraints have been respected during the observation. The QC0 checks are done on raw data.

The SM observer receives a QC0 report which lists all the programme-specific science files, their user-defined constraints (as read from the OB Repository which was filled from P2PP), and the actual QC0 parameters during observation (as read from the Ambient Database which is fed from the Ambient Site Monitor).

The data are checked for the following constraints:

  • airmass,
  • moon distance,
  • fractional lunar illumination (FLI),
  • seeing.

QC0 reports as part of a service mode package is shown on the ISAAC QC ServiceMode page.

Please note that for data acquired after October 2011, data packages are no longer created.



Quality Control Level 1 consists of quality checks on pipeline-processed data.

Most of t he QC1 parameters are provided by the ISAAC pipeline in the header of the pipeline product files, others are measured by post-pipeline procedures, on master calibration files and reduced files. The purpose of measuring QC1 parameters is:

  • to assess the quality of calibration products (e.g. noise properties, dispersion solution),
  • to compare with expected/nominal values (e.g. resolution),
  • to assess the performance of the instrument (e.g. efficiency),
  • to monitor efficiency of master creation process (e.g. reduction of random noise).

The result of the QC1 process is used to

  • decide whether master creation data are certified or rejected,
  • assess the quality of the reduction process.

All master calibration data created by QC Garching are quality-checked. Apart from measuring QC1 parameters, these files are also checked for "unusual" effects like overexposure, misalignment of gratings etc.

The QC1 data are internally used for decision making. They are also provided in a public database as part of the ESO Science Archive Facility.



Trending is monitoring QC1 parameters over time (e.g. detector ron as function of time).

Main results are:

  • monitor instrument health,
  • detect long-term trends,
  • detect sudden changes (e.g. misalignment of gratings).

There is a easy to use public ISAAC QC1 database .