Important recent changes (since Periods 92 and 93) regarding Paranal instrumentation and facilities

UT instruments and facilities

UT1 - Antu

  • CRIRES is taken out of operations as of July 17th, 2014 to undergo a major upgrade to transform it into a cross-dispersed echelle spectrograph. It is therefore not offered in Period 94.
  • Instead, NACO is offered on the Nasmyth A focus during Period 94  with a limited list of offered modes.
    • NAOS:
      • VIS & IR wavefront sensing
      • Pupil tracking
    • CONICA:
      • Imaging without chopping, including APP and NoAO; usage of the Mp filter is only possible in VM
      • Cube mode
      • Focal plane AGPM coronography, only in VM
      • Wollaston/HWP polarimetry, only in VM
      • Spectroscopy, only in VM
      • SAM/SAMPOL, only in VM.
    • The following modes are not offered: LGS, SDI+, 4QPM/Lyot coronography, APP spectroscopy.
    • The re-installation and commissioning of NACO on the UT1 Nasmyth A focus is planned to be completed by early September 2014: users are warned that this move has a non-negligible risk of failure.
  • KMOS 
    • KMOS has been in operations since Period 92.
    • The arm allocation tool KARMA now offers the possibility to exclude individual arms from the arm configuration. Please consult the KMOS news page to confirm which arm is not available for which period.
    • A month-long intervention to improve the reliability of the arms is expected to take place early in 2015.

UT2 - Kueyen

    • XSHOOTER is offered back on the Cassegrain focus of UT2, pending a final decision not yet taken at the time of issueing the call.
    • The Atmospheric Dispersion Correction (ADC) systems on the UVB/VIS arms are not reliable. Since August 1st, 2012, the ADCs have been fixed in their non-deviant position. Data obtained in this configuration can be reduced by the pipeline without significant degradation. Updates on the status of the ADCs can be found on the XSHOOTER news webpage. The latest version of the user manual provides plots for helping users prepare observations without ADCs. Users are recommended to carry out observations at the parallactic angle whenever possible or to take special care on the airmass constraint to avoid flux loss. XSHOOTER will likely be taken out of operations for several months to install re-designed ADC systems in the future. As a consequence, Large and Monitoring Programmes using XSHOOTER will not be accepted in Period 94.
    • As of Period 93, XSHOOTER  offers a new imaging mode using the Acquisition  and Guiding  camera.  In combination with slit or IFU observations, this mode will allow the users to take images of their object in various bands. However,  in parallel, only the  last snapshot of the  acquisition sequence per se  - i.e, in the acquisition template - will be saved instead of a snapshot at each offset as it is currently done.  More details can be found in the User Manual and in the News webpage.

UT3 - Melipal

  • Installation of SPHERE on the Nasmyth A platform is expected to take place during Period 93, followed by commissioning periods extending to Period 94.
  • VIMOS:
    • A review of the current policy of calibrating all the MOS modes at night is taking place. The expected outcome is that all MOS modes can be calibrated during the day, with the possible exception of the HR_blue mode. All IFU modes will continue to be calibrated during the night.
    • No Large or Monitoring Programmes are accepted for VIMOS due to a significant number of existing commitments, including a new ESO Public Survey. See the Call for Proposals for Period 94 for details.
    • Pre-imaging data taken before June 2011 is not valid any more for mask creation.
  • VISIR underwent a major intervention during Period 89. However, as the properties of its new detectors are not within specifications, it has been taken out of operations since Period 91. A new intervention to replace the spectroscopic detector will take place during Period 93 with a new commissioning expected to take place in Period 94. It is not offered in Period 94.
  • ISAAC was decommissioned in December 2013 and is no longer offered.

UT4 - Yepun

  • HAWK-I is offered again on the Nasmyth A during Period 94. Fast photometry will be offered in Period 94 both in Visitor and Service mode. See the User Manual for details.
  • SINFONI: Since Period 93, a new Pupil Tracking mode has been offered with NGS in both visitor and service modes. It allows to provide Angular Differential Imaging (ADI), in wavelength slices. Preliminary tests show that a ~8 magnitudes contrast (at 5 sigma significance) is achievable at distances 3 to 5 lambda/D (~ 0.17" to 0.43") from the primary star. However potential users should pay special attention to the restrictions listed in the section 2.9 of the User Manual, especially on the placement of the primary star as well as the flux limit. See the User Manual for details.
  • MUSE, the Multi-Unit Spectroscopic Explorer, enters in operations in Period 94. MUSE is a second-generation VLT instrument located on the Nasmyth platform B. It is a large-format integral-field spectrograph, based on image-slicing technology, and has a modular structure composed of 24 identical Integral Field Unit modules that together sample a contiguous 1 arcmin2 field of view in Wide Field Mode (WFM) sampled at 0.2 arcsec/pixel. MUSE will initially be used in seeing limited WFM only.
    MUSE will later exploit the VLT Adaptive Optics Facility in combination with the GALACSI AO module. When offered, it will provide Ground Layer AO correction for the WFM. In the future, a Narrow Field Mode (NFM) will also be made available, and will cover a ~7.5 arcsec2 field of view sampled at 0.025”/pixel with Laser Tomography AO correction.
  • No Large or Monitoring Programmes will be accepted on any UT4 instruments due the foreseen Adaptive Optics Facility installation and commissioning activities.

Visitor focus

  • No focus for Visitor Instrument is available on the VLT in Period 94.

VLTI instruments and facilities


  • During Period 94, the laboratory will undergo major modifications in view of the arrival of the 2nd generation instruments GRAVITY, MATISSE as well as ESPRESSO which will go in the nearby incoherent combined focus. MIDI, AMBER and the Visitor Instrument, PIONIER, are offered in Period 94 until the start of the activities, tentatively expected for early 2015.


  • No new baseline is off ered in Period 94. Note that station J3 may not be accessible during part of the period, in which case it will be replaced by station I1. For a list of all the o ffered baselines in Period 94, see the VLTI Configuration Overview page.   


  • MIDI is expected to be decommissioned during Period 94, therefore no Large or Monitoring Programmes will be accepted for this instrument.
  • AMBER:
    • Thanks to an improve polarization control, AMBER has gained 0.5 magnitudes in all spectroscopic modes. This gain is in addition to the previously announced gain of 1 and 0.5 magnitude in H and K bands because of the intervention on the cryogenic spectrograph. See the updated table of the limiting magnitudes as function of atmospheric conditions and observing modes.
    • Since Period 93, AMBER can be used in a container of CAL-SCI-CAL-SCI-CAL, with a 100 minutes of total execution time. The use of this sequence is limited to low spectral resolution and under seeing<1.2" and thin cloud coverage condition. A waiver needs to be requested. Regular rules regarding successful execution of containers with long execution times apply, i.e. the grading will be based on the first CAL-SCI-CAL sequence only.
    • Since Period 93, AMBER execution times for MR and HR modes have decreased from 25 to 20 min for a single band OB.
    • No Large or Monitoring Programme for AMBER will be accepted in Period 94 due to possible future change.
  • VLTI Visitor instrument:
    • PIONIER is a visitor instrument installed at VLTI that combines four AT or UT beams since october 2010. It has been mostly operated by the PI team until Period 92. Since Period 93, VLTI users have the possibility to submit proposals for PIONIER provided they have the agreement of the instrument PI, Dr. Jean-Baptiste Le Bouquin <> at least two weeks prior to submitting their proposal. Since PIONIER is a visitor instrument, observations can only be carried out in Visitor Mode (or possibly in designated Visitor Mode in the case of runs shorter than 1 night, see Section 5.1.2 of the Call for Proposals). Large or Monitoring programmes with PIONIER will not be accepted.
      The PIs applying for time should understand that ESO offers its support as a best effort basis. ESO's instrumentation staff will ensure PIONIER's refilling and alignment at the beginning of the night. However, ESO shall not be held responsible for the technical downtime due to PIONIER operation. The PIONIER PI team shall not be held responsible for the technical downtime either and will offer its support on a best effort basis. However it should be noted that technical dowtime with PIONIER is relatively rare and that observers are now trained to handle most of issues.
      PIONIER's data will be archived in the ESO archive and subject to the usual proprietary period of 12 months.  PIONIER's PI team will share the data reduction software (DRS) with its associated documentation. The DRS produces calibrated oifits files.
      Under the conditions described above, PIONIER is offered to the general community with a fixed dispersion of 3 channels accross the H band. Its sensitivity is H=7.5 under good seeing conditions (0.8"). A different setup requires the collaboration of a member of the PI team and its presence at Paranal during the observations.
  • Given the arrival of the second generation VLTI instruments, ESO cannot guarantee the availability of a VLTI visitor focus after P94.

Survey Telescopes and Instruments



  • Only Chilean and GTO programme proposals are accepted on VST/OmegaCAM in Period 94 to ensure the timely progress of the ongoing Public Surveys.
  • The installation of an improved baffling mechanism on the VST is taking place early 2014. The new baffles are designed to reduce the amount of stray-light component in OmegaCAM images. Once completed during the first half of 2014,  it is expected that the sky concentration effect in the central parts of the images will be reduced, therefore improving flat fields and reducing the overall sky background. These baffles should also allow more observations of targets closer to the Moon. OmegaCAM users are invited to follow the OmegaCam News page, where a quantitative analysis of the changes will be made available.