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version of this description:  P87 (April 2011)


Data packages have been delivered for period P87 (April-September 2011) and before. For new data, acquired after the begin of October 2011, data packages are no longer created. Users can access their raw data in electronic form through the ESO User Portal.

Data for VLT pre-imaging runs are processed and delivered as before.

For completeness, the structure of the historical packagesis described below.

Science data have been processed by the pipelines with the best available calibration data. Please note that ESO is not assuming any responsibility in respect to the usefulness of the reduced data. The adopted reduction strategy may not be suitable for the scientific purpose of the observations.


The top-level structure of the data package is as follows:


For each observation block (OB) that has been executed on Paranal, you find all measured raw data (FITS files) in a directory named by the OB number (FITS key HIERARCH.ESO.OBS.ID). If pipeline products exist, these are also added in the OB directory.

The GEN_CALIB directory collects all those calibration files (raw and products) that have been measured as part of the regular calibration plan, and calibration frames of a general nature (like static line tables). The GEN_INFO directory has general information, like data reports and night logs.

The tree shown above is the logical structure, which means that this is the way the data have been organized before they have been put onto media. Depending on the size of your package, the directories may be distributed across several media. It is a good idea to create the original tree on your local disk and then copy all files from the media into this tree.


<OBS_ID> (e.g. 179211)

For each executed observation block of your run, the package contains a directory with all measured data from that OB. All data under <OBS_ID> carry your run ID.

Note that some of your OBs may have been executed more than once. In particular, if time permitted, observatory staff try to re-execute OBs which produced data clearly out of the specified constraints. Check out the NIGHTLOG.html file for details (go to "OB information"). All data from OBs that have been executed multiple times are found in the same directory.

Each OB directory is further subdivided into subdirectories for science frames, calibration frames, and log files. In many cases, there will be science data only, but there may also be OBs with attached calibration data:



All acquisition frames (DPR.CATG=ACQUISITION) from the OB are contained in this directory. This directory only exists if such data exist.


All raw science frames (DPR.CATG=SCIENCE) from the OB are contained in this directory.


Here you find the pipeline-processed science data. The naming scheme can be found here.


If measured, raw calibration frames (DPR.CATG=CALIB) produced by the OB are contained in this directory ("attached calibrations"). These are the ones which have been taken upon user's request in addition to the ones from the calibration plan.

Calibrations measured as part of the regular calibration plan are stored under the GEN_CALIB directory.


The pipeline products of the raw attached calibrations are delivered here.

The CALIB products are renamed. The naming scheme can be found here.


This directory holds logging information about processing and packing of your data:

  • Association Blocks (.ab)
  • association logs (.alog)
  • logs of the pipeline processing (extension .rblog)
  • scoring results (.html) (optional)
  • extraction from the nightlog, OB grade, QC0 report (.qcm)
  • a reduction comment (.cmt) (optional)


  • Association Blocks (ABs) are text files which contain all the information required to pipeline-process and pack data. This information includes the reduction recipe, the input raw file(s), the calibration products needed for processing, and the names of the final products. More ...
  • Association logs are delivered since P80. They are a simplified version of ABs, designed to provide the association information essential for the user. More ...
  • The pipeline processing log is a record of the science reduction process, with a detailed log of reduction steps, results etc.
  • The scoring report is intended to give some feedback about the data quality. It is still experimental. More ...
  • The nightlog file is an extracted version (per OB) of the summary qc0 report and the NIGHTLOG.html file (see below). More ...

That directory in addition holds QC plots, if available.


This directory collects all calibration frames from the regular calibration plan that are associated to your science data. It also contains their pipeline products, and calibration frames of a general nature (like static line tables). Calibrations that have been measured by user-defined OBs and that have been used for pipeline processing of science data may be included here in addition.

The directory has four subdirectories (gen, logs, proc, raw), two of which have further fine-structure:

cal1 cal2 cal3 cal4
cal1 cal2 cal3 cal4


Raw calibration files. These divide into raw file types (e.g. BIAS, FLAT etc.; see instrument specific section below).


Calibration products derived from the raw calibrations. These divide into file types like the raw calibration files, see instrument specific section below.

The CALIB products are renamed. The naming scheme can be found here.


Association Blocks, association logs and processing logs for the calibration files under GEN_CALIB. There might also be scoring logs (.html files).


General calibration data of static nature.

[Archive] Additional or missing raw calibration files may be retrieved anytime from the generic ESO Archive form, or from the instrument specific forms.

Calibration data are public immediately while SCIENCE data normally have a proprietary period of one year.


This directory hosts some general information. It has the following subdirectories:

ObservingReports nightlogs, OB report (HTML files), association report
scripts executable scripts (presently one: print_all_reports)



The data package contains the following report files:
README.html the package portal page: point your browser here to find all information top
ServiceMode.html this file top
product_codes.html a table describing the naming scheme for product files top
archive_<RUN_ID.txt list of all proprietary files (SCIENCE, attached CALIBs) as read from the archive GEN_INFO
qc0_<RUN_ID>.txt list of all SCIENCE files, containing the comparison between the user constraint set and the actual values GEN_INFO
NIGHTLOG.html set of html files with nightlog, OB and association information GEN_INFO/ObservingReports
list_sciRaw_<OBS_ID>.txt etc.
summary report of the fits files in each directory (these files are provided in text [*.txt] and PostScript format)  all data directories

The executable script print_all_reports under GEN_INFO/scripts can be used to print all postscript files in your package.

Archive report: archive_<RUN_ID>

While the above listings are about files in the package, the archive report is the result of a query to the ESO Archive. It is useful as a check on the completeness of the data package. All files created by OBs which have been generated by the PI are listed here. The list includes all SCIENCE files, and the attached calibrations, and acquisitions, if applicable.

archive report
keyword table
sample file

QC0 report: qc0_<RUN_ID>

This report is sent only for Service Mode runs.

This file contains a report of quality control parameters ('QC level 0' where level 0 stands for Quality Control without pipeline processing) for your raw SCIENCE files. These parameters are airmass, seeing, moon distance, and fractional lunar illumination. They have been measured on site (column 'msrd'). They are compared to the required values as defined in your OBs ('targt') and flagged (OK/NOK).

The list is intended to give a rough indication of whether or not the required constraints have been fulfilled. They should not be interpreted in a too formal way, however. E.g., there may be cases where the seeing was worse than required, but this was compensated by a longer exposure time. Check the night reports for details.

Note that the seeing values reported here are DIMM seeing values, they are not measured on the frame. If the alarm flag ("NOK") is set in the SEEING column, the DIMM seeing value was larger than your seeing constraint during the indicated obseration. However, in many cases, the delivered seeing in the instrument focal plane is better than the DIMM seeing. Whenever possible, the on-site astronomer has measured the focal plane immediately after or during execution to determine the success or failure of your observation. Thus, your observation may have been completed within your specifications, even if the SEEING alarm flag is set. Please review the affected observation carefully and check the night reports for details.

QC0 report
keyword table
[keyword table
sample file (.txt)  
[qc0 table]

Night logs, OB logs and Association report

This is a set of HTML files with night log information, OB grading information and data association information. All relevant information about the nights contained in your package is included here, as well as information about each OB in your delivery.

Point your browser to GEN_INFO/ObservingReports/NIGHTLOG.html (or start from the package portal page, README.html) and navigate per night (labeled as 1), per OB (2) or per set of files (3).

The HTML files also come as stripped-down, printer-friendly versions. The files are organized to have a summary on top, and details below.

You can use either the navigation bar to jump to a specific night/OB/set of files, or use the up/down arrows (night logs only) to browse sequentially. The OB navigation bar (2) uses colour coding to give you a quick impression about OB grading. There are additional links to ambient condition information.

The association report (3) organizes your data and their association. It has two main levels: the OB (observing block), and the AB (association block) which collects raw file(s) and associated information like product files, calibration files, log files etc. This report gives you an impression how the data in your package are logically linked, while the listings in each directory give you a table of contents. File names in the association report may show up several times, e.g when a calibration file has been used for processing more than one science file.


  • The external links (like the ASM links: seeing, sky transparency etc.) will only work with network connection.
  • The ASM links require java-enabled browsers.
  • The navigation bars read best with style-sheets and java-enabled browsers.
Sample nightlog files


Known IRAF problems

  • Filename Length. To display or manipulate the FITS files with older versions of IRAF (before 2.11), you can:
    - copy these FITS files to your hard-disk and rename them with filenames <= 32 characters in length;
    - create symbolic links with filenames <= 32 characters in length to your DVD files.

  • Header Interpretation. ESO FITS files use the ESO HIERARCH FITS keyword extensions standard to all ESO telescopes. Note that IRAF treats all ESO HIERARCH header lines as COMMENT lines, i.e. IRAF and IDL cannot automatically interpret the information provided in ESO HIERARCH header lines. The problem may be solved using the tool hierarch28. Find information about this tool here.

  • RA, DEC. Please note that the RA and DEC keywords are recorded in degrees. To translate these keywords so that they can be used by IRAF you have to use the asthedit task in the noao.astutil package. The help file for this task gives an example of how to translate the ESO format to the IRAF format.

Stand-alone FITS handling tools

Find information about FITS header handling tools (e.g. dfits, fitsort, hierarch28) here.


The rest of this page contains an overview of the structure and content of the data packages for UVES as a standalone instrument (also called UVES-Echelle) and for UVES as part of the FLAMES instrument (FLAMES/UVES, UVES-MOS, or UVES-Fibre). FLAMES programmes using both UVES and GIRAFFE spectrographs ("COMBINED mode") receive two separate sets of media, one for the FLAMES/UVES data and one for the FLAMES/GIRAFFE data. Both sets are usually shipped in one single package.

The description of the Service Mode package for FLAMES/GIRAFFE data is found here.

For further information about UVES data and QC have a look at:


The renaming scheme for UVES and FLAMES/UVES SCIENCE product files can be found here.
The ONLINE version is here.


The UVES raw and processed calibrations are mostly produced by the calibration plan. Only exception are attached flat calibrations as specified by the user.

More about calibrations ...

The GEN_CALIB directory for UVES data is structured as follows:


This directory collects all raw calibration frames that are associated to your science data, and that have been measured as part of the regular calibration plan. It also contains their pipeline products and calibration frames of a general nature (like static line tables). Calibrations that have been measured by user-defined OBs and that have been used for pipeline processing of science data may be included here in addition. The directory has four subdirectories, gen, logs, proc and raw. The proc and raw directories have further fine-structure:



UVES-Echelle, UVES-MOS Detector bias frames BIAS
SPEC_ARC UVES-Echelle Spectroscopic arc lamp exposures LAMP,WAVE
SPEC_FLAT UVES-Echelle Spectroscopic flat field exposures


SPEC_FLAT UVES-MOS Slit flat fields without fibre system LAMP,SFLAT
SPEC_OTHER UVES-Echelle Order definition flat fields LAMP,ORDERDEF
SPEC_OTHER UVES-MOS Order definition flat fields LAMP,ORDERDEF,SimCal
MOS_ARC UVES-MOS Arc lamp exposures through fibre system LAMP,WAVE,OzPoz
MOS_FLAT UVES-MOS Flat field exposures with fibre system LAMP,FLAT,ALL,OzPoz

Raw calibration data are described here: UVES and UVES-MOS

Calibration products derived from the raw calibrations. Please look at the UVES calibration pipeline or UVES-MOS calibration pipeline pages for descriptions of the products. The renaming scheme for UVES and FLAMES/UVES CALIBRATION product files can be found here.
The ONLINE version is here.

You can expect the following static calibrations in the gen directory

thargood_3.tfits LINE_REFER_TABLE reference line table
atmoexan.tfits EXTCOEFF_TABLE extinction coefficients table (only UVES-Echelle)
master response curves for flux calibration (only UVES-Echelle), available for central wavelengths 346, 390, 437, 564, 580, and 860nm

[Archive] Additional or missing raw calibration files may be retrieved anytime from the  ESO Archive. Calibration data are public while SCIENCE data have a proprietary period of one year.

Some notes on calibration frames

For operational reasons, calibration products are created only for standard configurations. No solutions are produced for non-standard configurations. Hence such SCIENCE data are not reduced either. The UVES pipeline may well be able to reduce such non-standard data.

Bias frames usually come in sets of five raw files which are stacked to one master bias. They are provided only once per week since they are in general very stable.

The order definition flats (and the format check frames, usually not delivered) are for pipeline use. They are required for automatic recognition of the spectral format. If you plan to reduce your data with your own software, or with MIDAS in interactive mode, you will not need them.

UVES-Echelle flat fields: Day-time lamp flat fields usually come in sets of five raw files which are stacked into one master flat. The extreme blue settings (WLEN = 346 nm) have two different types of lamp flats: those taken with the usual flat lamp, and those taken with a deuterium lamp which provides higher response in the UV but has emission lines at longer wavelengths (see User Manual). Both sets of flats are delivered. Master flats are also created from both sets. The automatic pipeline reduces science data with the normal master flats only. Two different sets of flats also exist for science data using the Iodine absorption cell (600 nm): one using the normal flat lamp and one using the lamp plus the absorption cell. Both sets are delivered and used for master flats. The automatic pipeline uses only flats without absorption cell

UVES-MOS flat fields: There are two different varieties. The fibre flat fields are used to recognise the fibre postitions on the CCD frame. They come in sets of three raw files which have only odd numbered fibres, only even numbered fibres, or all fibres illuminated, respectively. Corrections of the blaze function and of pixel-to-pixel variations are provided by slit flat fields. They are taken at three different slit positions with a stack of (typically) three frames at each position.

Flux calibration (UVES-Echelle): For the purpose of flux calibration, a set of master response curves (UV_MRSP) is available in the GEN_CALIB/gen directory (for 346, 390, 437, 564, 580, and 860nm only). Further information about response curves and flux calibration can be found here.


Known reduction problems (UVES-Echelle)

Instrumental artefacts. Please look at the page about recent problems for recently discovered instrumental artefacts that are not yet mentioned in the User Manual.

High signal. Optimum extraction may face problems in cases of high signal. Check out here for details.

High airmass. In cases of blue spectra taken at high airmass (> 1.5), without the ADC, atmospheric dispersion may shift the bluest orders out of the extraction window, and their flux is lost to the automatic pipeline procedure. The data can, however, be recovered by manual extraction. Even at airmass 1.1, differential extinction spreads the spectrum by about 3 pixels for the bluest setup (346 nm).

Order indentification. In a few cases problems have occured with order identification in settings with 346nm central wavelength: the orders found by the pipeline in the order defintion flat and during extraction/wavelength calibration of the science frame may be different. This is not recognised by the pipeline and the lines in the final wavelength-calibrated spectrum appear shifted by one order. An example is given here where the overlap between an observation with 346nm and 437nm central wavelength is shown. The problem may be resolved by choosing a different order definition flat.

Sky emission lines. Optimum extraction may over/under-corrected bright sky emission lines by 5% or more.

Artificial lines. Series of artificial lines are occasionally seen around 607 nm and 638 nm in spectra reduced with optimum extraction. These features may be mistaken as telluric or real physical lines.

Attached red flats. The recommended exposure times for attached flat fields as given in UVES user manuals until version 19/02/2003 (including) have been longer than the values used for day-time calibrations. Therefore, one or two orders in the upper (MIT) chip of attached flats taken with the FF4 lamp (used for 860nm settings) may have maxima above 40000 ADU. This chip is not linear any more in this region and saturates soon. It is recommended to check carefully attached flats taken with FF4 before using them for calibrating science data. Flat fields taken with other lamps or taken within the regular day-time procedure are not affected by this problem.

BIAS level. Note in cases of high-precision reductions of faint sources taken in 2x2 binnings that there is a temperature dependence of the mean BIAS level especially for the red upper CCD, by about 2 ADU/K.

Seeing. If the seeing encountered during the SCIENCE exposure is less than the slit width, it might happen that wavelength shifts are introduced in the SCIENCE data if the object is not perfectly centered. This may be checked and corrected, at least in the red, with the telluric absorption lines.

Radial velocity correction. Until 2001-09-17 (date of acquisition), a bug in the radial velocity correction as calculated by the pipeline may have caused wrong values. Please check carefully (FITS keywords HIERARCH ESO QC VRAD BARYCOR and HELICOR; also stated in the listing file 'list_of_all_red.txt'). Remember that no correction is applied to the data. This bug is present in version 1.2 and earlier of the uves pipeline, and solved with version 1.3.

Known reduction problems (UVES-MOS)

Instrumental artefacts. Please look at the page about recent problems for recently discovered instumental artefacts that are not yet mentioned in the User Manual.

Extraction of 860nm data. The part of the spectra above 980nm is usually not extracted well by the pipeline recipe.

High signal. Optimum extraction may face problems in cases of high signal. Check out here for details.

Artificial lines. Series of artificial lines are occasionally seen around 607 nm and 638 nm in spectra reduced with optimum extraction. These features may be mistaken as telluric or real physical lines.

Errorbar values. The values in the ERR_MWXB_SCI files are about a factor of two higher than the statistical 1sigma errors.

UVES solar spectrum

A combined solar spectrum ranging from 3100 A to 10,200 A, taken at highest possible resolution with UVES, is available for reference purpose. Find details here.

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