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product names
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Data product names

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 NACO pipeline product names start with "NC_".

Dynamic calibrations. The following types of dynamic calibration products of NACO exist: (technical calibrations are not listed)

Code type of file PRO_CATG
ICTF twilight/sky flat MASTER_IMG_FLAT
ICZT table with zeropoints ZPOINT_TABLE
ICSR psf calibration star NACO_IMG_STREHL_CAL

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

Code type of file PRO_CATG
GCAT standard star catalogue IMG_STD_CATALOG

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. Most NACO products have the following scheme:



  • FILTER is the broad-, intermediate-, or narrow- band (e.g. Ks, or IB221, or NB217),
  • CAMERA is S13, S27, S54, SDI+, or L27,
  • DICHROIC is VIS, N20C80, N90C10, JHK, or K.
  • DIT is the detector discrete integration time
  • WINDOW is the size of the FOV (NAXIS1): F (full), or W (windowed)
  • READOUT_MODE is DR (Double_RdRstRd), FS(FowlerNsample), UC (Uncorr),
  • READOUT_NAME is HD (HighDynamics), HS (HighSensitivity), HW (HighWellDepth), and HB (HighBackground).
STD data have in addition the target name coded,


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


NC_DCAL_180101A_1_7892_S27_F_FSHS.fits: Master dark with DIT=1.7892 sec, S27 camera, no window (F) and Highsensitivity Fowler sampling read mode.

NC_ICTF_180210A_J_S13_VIS.fits: J-band twilight flat acquired with S13 camera and VIS dichroic.

NC_ICTB_180210A_J_S13_VIS.fits: corresponding bad pixel map

NC_ICZT_180517A_S264-D_Ks_S27_VIS.fits: photometric zeropoint table for star S264-D, Ks filter, S27 camera and VIS dichroic.

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