The reduction of VISIR 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 VISIR reduction pipeline.

The VISIR pipeline consists of a number of recipes. They are based on the ESO common pipeline library (CPL).

There are two different applications of the VISIR reduction pipeline:

• at the MELIPAL telescope (UT3) on Paranal, running in automatic mode,
• at HQ Garching run by the Quality Control Team in the optimized mode.

The automatic operational 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 not obtain the best possible results. This is due to the sequential operation: post observation calibrations and day-time calibrations are not available during night-time.

The optimized operational mode becomes possible when all data of a night including the associated day-time calibrations have been collected. Then the calibration data are sorted and assessed independently of their timestamp. The best possible master calibration data are created. Their quality is checked. They are finally associated with the science data of a night. In the future, the day-time master calibration may be also applied to the science data (flatfield correction). This is the way all calibration data in supported modes are reduced by QC Garching, as are all science data from Service Mode programs.

The VISIR pipeline presently supports most offered modes. The pipeline does not reduce images obtained with VISIR_img_obs_GenericChopNod template. Also, in current version (P75), the recipe visir_spc_phot does not work on cross-dispersed spectra.

QC Garching processes the following VISIR data:

• all pipeline supported calibration data taken with VISIR no matter whether in Service or Visitor Mode. Some of the calibrations taken for technical reasons (DPR.CATG = TECHNICAL or TEST) are also processed.
• all science data taken in VISIR supported modes taken in Service Mode.
  

The main functionalities of the VISIR pipeline are:

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

QC Garching creates

• calibration products from raw calibration data, both for Visitor Mode and Service Mode nights. These raw data are stored in the ESO Archive and are publicly available. 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 Service Mode programs, QC Garching runs the pipeline on all science raw data and associated them with the best available quality-checked master calibration data.

Programs performed in Service Mode receive a set of DVDs (or CD ROMs) which contains

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

All VISIR imaging and spectroscopic raw frames come in the following format:

• HIERARCH ESO DET CHIP ID = Visir
• HIERARCH ESO DET CHIP NAME = DRS_SiAs_256x256
• HIERARCH ESO DET CHIP NX = 256
• HIERARCH ESO DET CHIP NY = 256
• HIERARCH ESO DET CHIP TYPE = MIR