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Quality Control


The Quality Control Group in Garching provides quality checks of the NACO 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, ambient observation constraints),
  • Quality Control Level 1 (QC1, per pipeline product)
  • trending (parameters as a function of time)

The following type of QC products are provided

  • QC1 parameters of each pipelione processed calibration product (master calibration). These single numerical values accessible from a local database in plain ascii format.
  • QC1 plots for each calibration product, showing the most important properties. These ps format figures will be soon available for the most recent master calibrations.
  • Trending plots of several QC1 parameters, showing the long term behaviour of individual instrument properties. These plots are available in gif and ps format.
QC0 reports

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 ilumination (FLI),
  • seeing.
  • The Strehl ratio is measured by the NACO pipeline on Paranal using two PSF-CALIBRATOR frames of the NAOS reference object.

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

QC per product

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

Parts of the QC1 parameters are provided by the NACO pipeline in qc.paf 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, image quality,
  • to compare with expected/nominal values (e.g. gain)
  • 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.

For the moment, the QC1 data are internally used for decision making and building a trending database. It is planned to provide them as part of the SM package, as well as store them in the Science Archive.

In practice we launch for each piepeline product a qc script which generates a qc plot for that product showing the most relevant features of the product. Furthermore the qc scripts extract or determine QC1 parameters and store them in a database.


QC1, trending

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. oddeven column non-linearity effect of the detector).

There is an easy to use public NACO QC1 parameter interface .



All QC1 parameters are stored in the central ESO QC1 parameter database.

There is an easy access to public WWW interface including a plotting tool -- NACO QC1 database .

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