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Quality Control and
Data Processing

CAL | HC | refs | QC
Trending & QC1
general info
QC links:
General information | 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.

VISIR part

The VISIR pipeline is publicly available here. Under this link you also find the pipeline Users Manual. It supports data measured both before and after the upgrade.

Data format
General information | Data format

Raw Data

The VISIR file format after the upgrade, i.e. for P95 (April 2015) and later, has fits files where all data is stored in extensions. The primary header unit is empty:

  imaging spectroscopy
format (X,Y), 1x1 binning 1024 x 1024 px 1024 x 1024 px
half-cycle frames no 2 per chopping cycle
integration frame yes (1 per file, i.e. nodding position) yes (1 per file, i.e. nodding position)


Pre-upgrade raw files were fits without extensions, detector size was 256 x 256 px.

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