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Pipeline product naming scheme

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product names
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general NACO


The names of all 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 parameter values all recognizable from the product name.

Since the begin of period 75 (April 2005), both science and calibration product files are renamed. (Actually, there was a transition phase extending for some instruments from April towards the end of the year 2005).

Before that date only calibration products followed the common scheme which is described here. (Some instruments had their own naming scheme which is described below, if applicable).

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

Instrument code

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

Type of product

Next, the product type is coded. The full value is coded in the fits header key HIERARCH.ESO.PRO.CATG. A short form of this tag is coded in four characters being unique per instrument:
1st letter M or P calibration product
  S science product
  G general calibration product (as of P82)
2nd to 4th letter ... type of product


All NACO pipeline product names start with "NC_".


NACO calibration products come in two flavours: dynamic ones (being updated regularly, short validity), and static ones (never or rarely updated). Both product types are delivered in the data packages and stored in the archive. The static ones (also called general calibration products) are also delivered in the public pipeline releases.

Dynamic calibrations. The following types of dynamic calibration products of NACO presently exist:
DCAL dark average NACO_IMG_DARK_AVG yes
DCAH dark, hot pixel map NACO_IMG_DARK_HOT yes
DCAC dark, cold pixek map NACO_IMG_DARK_COLD yes
DCAD dark, deviant pixel map NACO_IMG_DARK_DEV yes
ICLF internal lamp flat field, imaging MASTER_LAMP_FLAT yes
ICTF twilight/sky flat field, imaging MASTER_IMG_FLAT yes
ICTB twilight/sky flat field imaging, bad pixel map MASTER_IMG_FLAT_BADPIX yes
ICTE twilight/sky flat field, imaging, error map MASTER_IMG_FLAT_ERRMAP yes
ICTI twilight/sky flat field, imaging, interception MASTER_IMG_FLAT_INTERC yes
ICZT standard star, imaging, table ZPOINT_TABLE yes
ICZP standard star, imaging ZPOINT yes
ICSR strehl ratio, imaging NACO_IMG_STREHL_CAL yes

top Static calibrations. With P81 (April 2008), the static calibration products are also named according to the standard NACO naming scheme. Before that date, their names did not follow a strict naming scheme. The following table lists the codes in the new name scheme:

GCAT standard star catalog IMG_STD_CATALOG no

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

top Date of origin, version

The date of origin is identical to the date of the raw data measurement. It is coded as, e.g., 051015 for Oct 15, 2005.

The version of a file is indicated by capital letters always starting with A. Versioning is supported for certain types of files, see the above table. In all other cases, only one version per day is created (always A).

top Instrumental parameters

The instrument parameters characterizing a setup are included in the product name. Most 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.

Master biases follow different scheme:



  • DIT is the detector DIT,
  • CAMERA is S13, S27, S54, SDI+, or L27,
  • WINDOW is the size of the FOV (NAXIS1): F (full), or W (windowed)
  • READOUT_MODE is DR (Double_RdRstRd), FS(FowlerNsample), UC (Uncorr), while READOUT_NAME is HD (HighDynamics), HS (highSensitivity), HW (HighWellDepth), and HB (HighBackground).

STD data have in addition the target name coded,

Static calibration products contain some self-explanatory string like e.g. NC_GCAT_080314A_IMG_STD_CATALOG.fits for the standard star catalog table.


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

top Examples

NC_DCAL_090825A_0_5_S27_F_DRHS.fits: master dark average, DIT 0.5 s, camera S27, full window, DoubleRdRstRd HighSensitivity read-out and detector modes; taken on date 2009-08-25 (first one on that date).

NC_ICLF_070515B_Ks_S13.fits: combined lamp flat, filter Ks, camera S13; taken on date 2007-05-15 (second one on that date).