This page provides information about pipeline processing and data types.

Raw data are selected, associated and inserted into a reduction mechanism which produces calibration products, science products and quality control information. This mechanism is the data processing pipeline. There is one such 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.

Before October 2011 QC Garching processed science data, using the best available, quality-checked master calibration data. As of October 2011 this service is not offered anymore.

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 purposes 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 following table shows some of the main keywords for the different raw files

type of observation	type of object	template	DPR CATG	DPR TYPE	DPR TECH	comment
PRISM-GRISM transmission with filters	technical calibration	MIDI_autotest_tec_dsptrn	CALIB	WAVE	SPECTRUM
reference pixels		MIDI_autotest_tec_refpix		FMTCHCK	IMAGE
detector linearity		MIDI_autotes_tec_detlin		FLAT	IMAGE or SPECTRUM
detector read-out noise		MIDI_autotest_tec_detron		BIAS	IMAGE
wavelength calibration		MIDI_autotest_tec_wavecal		WAVE,FOIL	SPECTRUM
acquisition	astronomical calibrator or science target	MIDI_starintf_acq	CALIB or SCIENCE	COARSE,OBJECT	IMAGE
fringe search		MIDI_starintf_acq	CALIB	FRINGE_SEARCH,OBJECT	INTERFEROMETRY	can be split in several files
fringe acquisition		MIDI_starintf_obs_fringe	CALIB or SCIENCE	TRACK,OBJECT,DISPERSED	INTERFEROMETRY	can be split in several files
				TRACK,OBJECT,DISPERSED,SCIPHOT
photometry				PHOTOMETRY,OBJECT	IMAGE,WINDOW.CHOPNOD	beam A/B
				PHOTOMETRY,OBJECT,SCIPHOT
end of template				OTHER	OTHER	empty file