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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.


The XSHOOTER pipeline is publicly available here. Under this link you also find the pipeline Users Manual.

It has two modes of operation. In the physical model mode a configuration file with instrument model parameters is updated by analyzing the various calibrations. This mode is used for Quality Control as it provides more direct information on the instrument health. Therefore also the automatic processing of science data is done in this mode. The polynomial mode instead fits the calibration data with polynomials.


Find the description of XSHOOTER data processing and pipeline recipes for calibrations here and for science data here.

Data format
General information | Data format


XSHOOTER UVB-arm raw frames have a size of 2144 x 3000 pixel (unbinned) or 2072 x 1500 (1x2 binning) or 1072 x 1500 (2x2 binning).

XSHOOTER VIS-arm raw frames have a size of 2106 x 4000 pixel (unbinned) or 2106 x 2000 (1x2 binning) or 1052 x 2000 (2x2 binning).

XSHOOTER NIR-arm raw frames have a size of 2048 x 1100 pixel.

XSHOOTER AGC raw frames have a size of 562 x 528 pixel.

Find more details about the X-SHOOTER detectors here.

The UVB- and VIS-arm optical CCDs can be operated in low gain and high gain mode, which does not affect the number of frame pixel.

The NIR-arm detector is operated in non-destructive read out mode. NDIT exposures are averaged on the chip. For signals > 40000 ADU, the detector pixel switches from interpolation mode to extrapolation mode. Details are given in the XSHOOTER User manual.


The raw frames don't contain any fits extensions.


Pipeline products have varying data formats. More details are described here.

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