Quality Control and
Data Processing

The names of all calibration pipeline products follow a certain naming convention. This is done to have human-readable rather than technical file names. The naming scheme has been chosen to have the type of product, its date of creation, and its pipeline-relevant setup values recognizable in the product name.

The general format of user-oriented product file names is the same for all VLT/VLTI instruments.

On the archive interface, the master calibrations can be associated to science files and downloaded. Then they carry technical filenames (the archive filename ARCFILE). In order to rename them to the original filenames, search for the fits header key ORIGFILE. The naming scheme of ORIGFILE is described here.

Instrument code

All product names start with two letters which are specific for the instrument. For instance: UVES product names start with 'UV', VISIR names with 'VR'.

Product category

The full value of the product category is coded in the FITS header key HIERARCH.ESO.PRO.CATG. A short form of this tag is encoded in four characters being unique per instrument:

1st letter	M or P	calibration product
	G	general (static) calibration product
2nd to 4th letter	...	type of product

Calibration products come in two flavours: dynamic ones (being updated regularly, short validity), and static ones (never or rarely updated). The static ones are also called 'general' because they often are not derived from raw data (like e.g. a line catalogue).

Both product types are stored in the archive and are available for download through the calSelector service. All GRAVITY pipeline product names start with "GR_".

Dynamic calibrations. The following types of dynamic calibration products of GRAVITY exist:

Code	type of file	PRO_CATG
PDRK	master dark	DARK
PBAD	bad pixel map	BAD
PFLT	master flat	FLAT
PWAV	wavelength calibration	WAVE
PP2V	pixel-to-visibility matrix	P2VM
PVIS	visibilities from calibrator	SINGLE_CAL_VIS or DUAL_CAL_VIS

Static calibrations. These are the codes for the static calibrations:

Code	type of file	PRO_CATG
GCAT	calibrator catalogue	DIAMETER_CAT
GDSP	dispersion model	DISP_MODEL
GEOP	earth orientation parameters	EOP_PARAM

The remaining part of the names follow the same convention as for the dynamic products (see below).

Date of origin, version

The date of origin is identical to the date of the raw data measurement. It is coded like, e.g., 191015 for Oct 15, 2019.

The version of a file is indicated by capital letters, starting with A. Versioning is supported when reasonable, otherwise it is always A.

Instrument parameters

The instrument parameters characterizing a setup are included in the product name. All pipeline products for GRAVITY have the spectral resolution mode (either LOW, MEDIUM, or HIGH) and the polarimetry mode (COMBINED or SPLIT) in their names. Calibrations that are not taken on sky have in additon the DIT, the visibility files have also the name of the calibrator star included.

Static calibration products contain some self-explanatory character string.

File name extension

All product files have extension .fits. They have either image format or binary table format.

Examples

GR_PFLT_180902A_HIGH_SPLIT_DIT0.3.fits: a master flat from 2018-09-02 taken with HIGH spectral resolution in SPLIT geometry and with 0.3 secs DIT.

GR_PVIS_180902A_MEDIUM_COMBINED_HD_209688.fits: visibilities derived from the calibrator star HD 209688 in MEDIUM spectral resolution and COMBINED polarimetry.