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Quality Control and
Data Processing

CAL | HC | refs | QC
Trending & QC1
general info
QC links:
General information | Raw Data format

General information


Pipelines are used at ESO to process both calibration data and science data and to retrieve quality information. There is a dedicated pipeline for each VLT and VLTI instrument. Find general information about ESO reduction pipelines here.


The main functionalities of the pipelines are:

  • create master calibration data,
  • reduce science frames,
  • extract QC information from the data.
QC Garching creates master calibration data from all raw calibration data. The raw data are stored in the ESO Archive and are public. They are quality-checked and used for data reduction and for trending.

For selected instrument modes, we offer science-grade data products processed with the pipelines.


There are two instances of the data reduction pipelines:

  • at the instrument workstation on Paranal, running in automatic mode,
  • at HQ Garching, run by the Quality Control Group in the optimized mode.
The automatic mode is used for quick look and for on-site quality control. It processes all raw data sequentially, as they arrive from the instrument. If calibration products ("master calibrations") are required for processing science data, these are taken from a database with standard, pre-manufactured calibration products. The automatic mode is not tuned to obtain the best possible results.

The optimized mode is the mode, which uses all data of a night, including the daytime calibrations. The calibration data are sorted and grouped according to their dependencies. Master calibration data are created. Their quality is checked.


The SPHERE pipeline is publicly available here. Under this link you also find the pipeline User Manual.

Raw Data format
General information | Raw Data format


IRDIS raw data come as FITS format data cubes with planes of size 2k x 1k and NDIT planes. The 2k x 1k planes contain side by side two images coming from two different optical paths of the IRDIS instrument. So far there is a discontinuity in world coordinates at columns x=1024.
IRDIS Technical PSF calibrator frames (an AO corrected internal lamp fiber image to check the AO performance of the CPI) come with planes of size NAXIS1=2048 and NAXIS2=256.


IFS raw data come as FITS format data cubes with planes of size 2k x 2k and NDIT planes. The 2k x 2k planes contain either images (e.g. detector flats, dark frames) or integral field spectra (IFU flats).


ZIMPOL raw data come as FITS cubes with two extension, one for each optical CCD detector. The raw data are binned resulting in a plane size of NAXIS1=1156 x NAXIS2=1024 pixel for each extension. The number of planes of the cube is even, as NDIT is even. This is because of the special detector operations mode. See SPHERE User Manual and references therein.

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