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XSHOOTER Quality Control
QC1 Parameters and Trending

CAL | HC | refs | QC
Trending & QC1
trending & QC1
Data Packages
Data Management
QC links:
Parameter Plots Tutorial Pages QC1 Database
detector bias  
linearity & gain   
distortion format check   
order definition   
2d map   
wavelength calibration   
lamps flat   
slit standard stars and science data      
IFU standard stars and science data  

Find here detailed information about the XSHOOTER trending plots and select plots and data for download ( UVB, VIS, NIR, all arms).


Some XSHOOTER calibration data are presently monitored to extract information about their quality and the instrument performance. The quality information is extracted into so-called QC parameters.

XSHOOTER calibration data are pipeline-processed to create calibration products. The quality of the products is measured by QC1 parameters. Most QC1 parameters are obtained by pipeline procedures; some are measured by post-pipeline recipes.

All measured QC1 parameters are stored in a database. Their evolution with time is evaluated by the trending process.



All XSHOOTER calibration products are quality-checked. While details of this process vary from case to case, some features are generally valid:

  • Raw frames and master frames are displayed and visually checked for anomalies.
  • When applicable, raw frames are checked for over-exposure (e.g. flats).
  • The distribution of pixel values is controlled in histograms. E.g., the distribution of pixel values in BIAS frames is checked to be consistent with statistical noise.
  • The product tables from format check and wavelength calibration frames are checked for number and distribution of fitted lines.

A calibration product is certified when experience shows that it measures the instrumental status in the proper way. This may mean that it complies with the expected result within certain limits. But it may also be true that it represents a valid outlier. E.g., after a realignment of a grating its X and Y shift against a reference frame will differ from the previous values, but this is a valid deviation.


The following properties of XSHOOTER detector and instrument components are trended:

  • bias level and read noise
  • detector parameters (gain and non-linearity)
  • dark current
  • format check (number of lines, residuals, gaps, stability)
  • order position (number of orders, residuals)
  • distortion (number of lines, residuals, gaps)

wavelength calibration (resolution, number of lines, shift w.r.t. 9-pinhole positions)

calibration lamps (flat, arc)