Important recent changes (since Periods 91 and 92) regarding Paranal instrumentation and facilities

UT instruments and facilities

UT1 - Antu

    • A major upgrade project to transform the instrument as a cross-dispersed echelle spectrograph has been approved. As a consequence the instrument will be taken out of operations for approximately one year starting likely in Period 95. Therefore Large and Monitoring Programmes using CRIRES will not be accepted.
    • A UNe wavelength calibration system may be in operation for P93 which typically has between 3 and 5 times more lines than the current ThAr lamp.
    • Calibration frequency may decrease during P93.
  • FORS2: Since P91, a new functionality has been added to the fast acquisition templates (including the RRM ones) for long-slit spectroscopy, spectropolarimetry, and spectrophotometry. It is now possible to align the slit along any direction defined by two objects and use several centering options.
  • KMOS  is in operations since Period 92.

UT2 - Kueyen

  • FLAMES: The UVES fiber 37 on plate 2 is broken since September 11, 2012. The latest attempt to fix it yielded 30% of the original transmission. Therefore the fiber will remain disabled until better results are reached or the fiber is replaced. Data obtained with the missing fiber can be reduced with the patched version of the FLAMES/UVES pipeline.  A tutorial showing how to prepare the observations avoiding this fibre is available on the phase 2 web page.

UT3 - Melipal

    • As of Period 92, XSHOOTER has been offered on the Cassegrain focus of UT3.
    • 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-deviation 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 during Period 94 or 95. As a consequence, Large and Monitoring Programmes using XSHOOTER will not be accepted in Period 93.
    • Starting  in P93, XSHOOTER  will offer 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.
    • Telluric standard stars are observed in nodding instead of staring mode since Period 91. The 400 kHz readout mode for the UVB/VIS arms is used independently of the readout speed used for the science observations. Detector binning will be the same as for the science observations. This change gives a better correction of the telluric emission and absorption lines as well as bad pixels, especially in the NIR arm. The provided S/N will be between 50-150 by default. Users requiring higher S/N are encouraged to submit their own telluric star OBs, in which case the corresponding execution time must be included in the time requested at Phase 1. There is no change for the IFU telluric standard stars observations.
  • ISAAC is being decommissioned in Period 92 and is no longer off ered.
  • Installation of SPHERE on the Nasmyth A platform is expected to take place during Period 92. Commissioning of the instrument will take place during Period 93.
  • 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.
    • 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. It is not offered in Period 93.

UT4 - Yepun

  • As of February 2013, PARLA, a prototype of the laser used by the coming Adaptive Optics Facility (see the AOF booklet in pdf format), replaces PARSEC within the Laser Guide Star Facility (LGSF). Thanks to the increase in delivered power and large improvement in reliability, the number of nights during which the LGSF can be used every month is significantly increased.
  • HAWK-I will be temporarily removed from the UT4 Nasmyth A focus during Period 93 and until it is necessary for AOF-related activities.
  • NACO will be temporarily o ffered on the UT4 Nasmyth A focus during Period 93 - until the focus is necessary for AOF-related activities - 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.

During Period 93, the following modes are not offered: LGS, SDI+, 4QPM/Lyot coronography, APP spectroscopy.

Because of the re-installation and commissioning activities associated with bringing the instrument to the Nasmyth A focus, it is expected that  NACO will only be operational in the course of May 2014: therefore, observing runs which can only be executed in April 2014 are unlikely to be allocated time.

Users are warned that the re-installation of NACO on the UT4 Nasmyth A focus is a risky move with a non-negligible risk of failure.

  • SINFONI: Starting in Period 93, a new Pupil Tracking mode is offered with NGS. 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. See the User Manual for details.
  • MUSE is expected to enter integration and commissioning during Period 92. Commissioning activities will continue during Period 93.
  • No Large or Monitoring Programmes will be accepted on any UT4 instruments.

Visitor focus

  • No focus for Visitor Instrument is available on the VLT in Period 93.



  • No new baseline is off ered in Period 93. 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 93, 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.
  • Since Period 91 MIDI can be operated with the FSU-A as an external, on-axis fringe-tracker. FSU-A works in K-band. When the science data are reduced using the fringe tracker data, MIDI+FSU-A with the ATs is able to attain a sensitivity for correlated fluxes similar to what used to be possible with the UTs. Because of the UT vibrations, however, the FSU-A offers no sensitivity advantage for the UTs, i.e. the limiting magnitude in the K-band for fringe recording is the same for the UTs as for the ATs. Observations with MIDI/FSU-A and the UTs can only be considered if a benefit over using the ATs is convincingly demonstrated (e.g. off-axis AO guide star availability). MIDI+FSU-A is only offered in the correlated flux mode.
    This configuration is only offered in visitor mode.
    Since ESO does not provide a reduction pipeline for the correlated flux mode obtained with FSU-A, it is only recommended for users with expertise in reducing correlated flux mode data.


  • Thanks to a recent intervention on the cryogenic spectrograph, AMBER has gained 1 and 0.5 magnitude in sensitivity in H and K band, respectively, in all spectroscopic modes. See the updated table of the limiting magnitudes as function of atmospheric conditions and observing modes.
  • Starting with 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.
  • For Period 93, AMBER execution times for MR and HR modes are decreased from 25 to 20 min for a single band OB.
  • No Large or Monitoring Programme for AMBER will be accepted in Period 93 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. In 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 delegated 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 beyond Period 93.



  • Only Chilean and GTO programme proposals are accepted on VST/OmegaCAM in Period 93 to ensure the timely progress of the ongoing Public Surveys.