The reduction of VIMOS data at QC Garching is done in a semi-automatic manner: raw data are selected and inserted into a reduction mechanism which produces

• calibration products and
• reduced science data.

This mechanism is the VIMOS reduction pipeline.

The VIMOS pipeline Data Reduction Software (DRS) is implemented in C.
Find general information about ESO reduction pipelines here.

Find the description of calibration processing, science reduction and recipes here.

There are two instances of the VIMOS reduction pipeline:

• at the telescope on Paranal, running in automatic mode,
• at HQ Garching run by the Quality Control Team in the optimized mode.

The automatic mode is used for quick look purposes and for on-site quality control. It processes all raw data sequentially, i.e. as they arrive from the instrument. It produces calibration products and reduced science data, but will usually fail to obtain the best results. It provides results for all standard and many non-standard VIMOS settings.

The optimized mode is the mode, which becomes possible when all data of a night have been collected, including the daytime calibrations. Then the calibration data are sorted and assessed independently of their timestamp. The appropriate master calibration data are created. Their quality is checked. They are finally applied to the science data of a night. This is the way all calibration data in supported modes are reduced by QC Garching, as are all science data from Service Mode programmes.

The VIMOS pipeline installed in Garching and on Paranal supports the IMAGING, the MOS modes and since May 2004 the IFU of VIMOS SCIENCE data. The standard setting is 1x1 binning, no windowing, low-gain for IMG and high-gain for MOS and IFU. The standard settings for grism+filter are: LR_red+OS_red, LR_blue+OS_blue, MR+GG475, HR_red+GG475, HR_orange+GG435, HR_blue with no order sorting filter.

QC Garching processes the following VIMOS data:

• all calibration data taken in VIMOS standard settings, no matter whether Service or Visitor Mode;
• all science data taken in VIMOS standard settings taken in Service Mode.
  

The main functionalities of the VIMOS pipeline are:

• create master calibration data,
• reduce science frames,
• provide QC1 parameters.

QC Garching creates

• master calibration data from raw calibration data taken in standard settings, both for Visitor Mode and Service Mode nights. The raw data are stored in the ESO Archive and are public. They are assessed and selected in terms of their quality and used for QC1 checks and trending;
• reduced science data for Service Mode nights. For SM programmes, QC Garching runs the pipeline on all science raw data taken IMAGING, MOS and IFU modes wiyh standard settings, using the best available, quality-checked master calibration data.

VIMOS SCIENCE data have been processed by the pipeline with the best available calibration data. Please note that ESO is not assuming any responsibility in respect to the usefulness of the reduced data. The adopted reduction strategy may not be suitable for the scientific purpose of the observations.

Programmes performed in Service Mode receive a set of DVDs which contains

• all raw science data,
• reduced science data,
• suitable calibration data (both raw and master),
• listings and logs,
• QC1 reports.

Raw VIMOS frames come in group of 4, one for each quadrant, and have the following CCD formats :

CCD formats are described here.

Master calibration files (master BIAS, master FLAT) have the prescan and overscan regions chopped off. Master files come in group of 4, one for each quadrant.

For 1x1 binning IMAGING master files have the format 2048x2440 px, MOS master files 2048x4096 px.

Raw calibration files, raw science files, and master calibration files, have the following approximate sizes in MB: