Paranal Science Operations

General Information

Paranal Science Operations (PSO) is the department of the La Silla Paranal Observatory that is in charge of the operation of the telescopes on Paranal. These telescopes are:

  • The four Unit Telescopes (UTs) forming the VLT.
  • The VLTI, which is the interferometric combination of either the UTs or the Auxiliary Telescopes (ATs).
  • The VST and VISTA survey telescopes.
  • And in the future: the ELT!

Watch live webcam pictures from the summit of Paranal. Go here for a real-time check of the atmospheric conditions on site.

If you are interested in working at Paranal, you are invited to inform yourself about the career prospects and working conditions in the PSO department. Also check out our alumni page to see where our previous department members are working now.


PSO News

  • October 2017: Users of designated visitor mode programs will be able to view from their computer at home the relevant operation panel in the Paranal control room, via the Paranal Observatory Eavesdropping Mode. Access credentials will be provided by the mountain staff in advance of the run.
  • April 2017: As of April 3, visitors at Paranal are asked to prepare their observations using the new web-based tool p2 that replaces p2pp3 (exceptions are users for VIMOS). This includes designated visitor mode.
    All visitors of upcoming runs are therefore encouraged to familiarize themselves with p2 in advance of their run. Main changes with respect to p2pp3 include:
    • OBs are created using a web browser without the need for installation of a dedicated software.   
    • Any OB created through p2 will be directly recorded in ESO’s database and hence become available in real-time at the telescope console in the Paranal Control Room [i.e. no need to export OBs and/or transfer OBs]
  • September 2013: As mentioned in the CfP for P93 (section 5.1.2), ESO reserves the right to allocate time in Designated Visitor Mode (dVM) on the VLT(I) telescopes instead of in regular Visitor Mode. This applies to any runs with a justified need for Visitor Mode observations and whose duration is strictly smaller than one night.
    PIs of such dVM runs are informed at time of the web letters that instructions for the relevant procedures are described under the section  “Information for Observers” at the URL: (this page).
  • January 2013: In our commitment to continuously improve the services provided to the community of ESO users, our operations model has recently undergone a reorganization of the day- and night- time tasks. The implementation of the related changes has started in January of 2013 and full deployment is expected to last until mid-2013. These changes aim at enhancing: 
    • the quality of the daytime support, in particular towards visiting astronomers (the nighttime support astronomer will most of the time also be available to help with the preparation of the science programs), and
    • the quality of the instrument support (documentation, science product and related calibration/reduction).
  • October 2012:
    • Deployment of new generation operations tools at all LPO telescopes, including vOT/P2PP3.
    • Discontinuation of DVD data backup for visitors and FTP transfer of ToO data. All data (science & calibrations) should now be accessed via the ESO archive.

Information for Observers

In the SciOps pages, you should find all the information you need for your observations from the time you have an idea of observations until when you finish processing your data. The menu on the left contains the list of the PSO pages for the astronomers, which are described in more details hereafter. Also, some useful ESO pages (not belonging to PSO) can be accessible from the left sub-menus and are explained in this page.

  • Preparing your proposals for observing time and your observations

  • Visiting astronomer coming to Paranal

    • Before your observation run: you should familiarize yourself with the technical documentation (see below), and with p2. This Visitor Information page contains the info you will need. From that page, you will also find information on the Computers at your disposal, as well as on the Data Reduction Software installed.

      Remember to prepare
      • a backup program in case of poor seeing, thin clouds or strong winds (usually implying targets with Dec < -25deg),
      • the list of additional objects you want to observe in addition to your approved targets
      and to request their approval well in advance using this procedure
    • Arriving on Paranal, you should also check out the practical information you should find in your room (or here as a PDF file)
  • Designated Visitor Mode Observations (dVM)

    • Although the preparation and execution of your dVM run are considered to be similar to that of a VM run, the preparation of the observing material should follow the phase2 guidelines.

      At least 4 days before your run please have your observation material prepared within p2, including the Readme file. To notify the mountain team that you are ready with your preparation, press the 'notify Paranal' button.

      The README should contain instructions for time critical observations, special calibrations, etc. and your Skype name and your contact phone number, in case realtime support is required from you during the execution of the observations.
      • BACKUP OPTION based on the previous standalone p2pp3 (to be used in case there are unforeseen problems with p2), is to send a tarball with the following material to
        • All OBs (science & special calibration) prepared (and verified) with the latest version of p2pp, exported to .obx format
        • README file with detailed instructions on the observing sequences, strategy of the observations, calibration needs, etc
        • Finding charts for all targets
        • Instructions for time critical observations, special calibrations, etc.
        • Your Skype name and your contact phone number, in case realtime support is required from you during the execution of the observations
    • Independent on when you submitted your material, you are requested to contact Paranal ( again 2-3 days before the start of your run to establish communication with the Operations Staff that will actually be executing your observations (e.g. to test skype connection / clarify final details / notify whether or not you will be available on skype).
    • In case of questions, please send an email to ''.
    • Similar to regular VM runs, designated VM runs are executed on a fixed time-slots and can be affected by changing meteo conditions or instrument failures.
    • As for VM runs, please submit in advance any request for  instrument setup changes or additional and backup targets.
    • Please do not forget to complete your end-of-mission report.
  • Service Observation

  • After the observations...

  • Special cases - Targets of Opportunity and Director Discretionary time:

    • DDT Instructions: how to apply for Director Discretionary time
    • RRM trigger Instructions for triggering Rapid Response Mode Observations.
    • RRM Status: log of the instrument status and of the RRM triggers.
    • ToO Policies: the rules governing the execution of ToO at the La Silla Paranal Observatory.
    • ToO Trigger form, to request the execution of an approved ToO observation.
  • Other policies

Technical Information