This section describes important changes which took place during Period 112, as well as changes expected to take place during Periods113 and 114.

Rapid Response Mode (RRM) activation policy:

The RRM policy changed starting in Period 105: on-going observations on any VLT instrument can be interrupted by an RRM triggered on that specific UT, even if the trigger requires a change of focus, unless the relevant programme is specifically protected against an RRM trigger (in case of strictly time-critical programmes). The change has been implemented at all UTs. More information on the Rapid Response Mode can be found on the Phase 2 page.

UT instruments and facilities

UT1 - Antu

• KMOS:
  
  • Since P112, the observatory only provides a telluric in twilight observed at an average airmass. Users must take this into account and provide their own tellurics concatenated to the OBs if a maximum difference of airmass or time is required by their science goals.
• FORS:
  
  • In the future, the Imaging (IMG) observations will no longer be accompanied by a standard field observation. The photometric calibration shall be performed using Gaia stars in the field of view. Once the tool is available, the users should check if there are suitable Gaia stars in their field of observations in the ObsPrep tool. In case that there are no Gaia stars available (~ 10% of pointings), and the user needs to calibrate their observations photometrically, then a standard field observation OB should be provided by the user, the time for which is accounted for from the time allocated to the user. ESO will continue to provide accompanying standard field observations until the ObsPrep tool is available. Moreover, because of a change in the FORS2 calibration plan, users should also be aware that absolute photometry down to the 3% level is no longer feasible. Furthermore, only extinction values will be possible to compute, using the standard fields or the Gaia stars.

UT2 - Kueyen

• FLAMES:
  • Fibre 54 on plate 1 has been taken out of service as it got damaged.

UT3 - Melipal

• SPHERE: 
  • For the star center observations (obs. Type=C), the WAFFLE pattern amplitude in all modes is calculated automatically and should be left as “AUTO” by default.

UT4 - Yepun

• MUSE:
  
  • The extension of the GALACSI NFM tip-tilt limiting J-band magnitude has been commissioned. Details are available on the news page of MUSE.
• ERIS:
  • All originally planned ERIS modes are now fully commissioned.
    

Incoherent combined focus

• ESPRESSO:
  • A new public version (3.2.3) of the ESPRESSO pipeline is available.

Visitor focus

• The UT1 Nasmyth A focus is not available for Visitor Instruments, due to the installation of the field corrector lens for MOONS.
  
• Potential users of a visitor focus are requested to consult the VLT Visitor Instruments page.

VLTI instruments and facilities

General:

• For new users to VLTI needing assistance to prepare their VLTI proposals, the community supported VLTI Expertise Centres - disseminated throughout Europe - can offer in-depth support. They also offer support for advanced data reduction and interpretation.
• Monitoring Programme proposals on the VLTI-ATs are accepted for both GRAVITY and for MATISSE without exceptions. Monitoring programmes on VLTI-UTs will be available again after the completion and characterization of the new adapative optics system (GPAO).

VLTI-UTs:

• Only the Natural Guide Star modes of the VLTI-UT Adaptive Optics (GPAO) is offered in P115: the visible mode (NGS_VIS, replacing the former MACAOs) and the infrared mode (NGS_IR, formerly called CIAOs). See the VLTI manual for details.

VLTI-ATs:

• ESO will continue a scheme to optimise operations for aperture synthesis with the VLTI. This scheme only applies to service mode proposals using ATs with PIONIER, GRAVITY and MATISSE. The reader is referred to the Period 115 VLTI manual for further details.
  
  

Instruments

• One VLTI visitor focus (VISITOR 1) is available. Potential users are requested to consult the VLTI Visitor Instrument page.
  
• GRAVITY is offered on all AT configurations as well as on all four UTs with the visible (MACAO) and infrared (CIAO, off-axis only) adaptive optics system in Service and Visitor modes.
  • The on-axis mode of the IR wavefront sensor CIAO cannot be offered for the time being due to critical problems that were identified during its commissioning.
  • ESO invites proposals with the goal of performing astrometric measurements (see, e.g., the following articles: Gravity collaboration, 2017 A&A 602, A94 and The Messenger 170, 10). Proposers who need help with the preparation of GRAVITY astrometric observations are invited to contact the ESO Helpdesk well in advance of the deadline.
  • Starting with P110 GRAVITY a new observing mode dual-field wide is offered for the UTs and the small & large configurations of the ATs. This mode allows fringe tracking from a target that is up to 30 arcsec away from the science target by using the VLTI Star Separators to separate the beams. The magnitude limits of the fringe tracker and acquisition camera and the expected sensitivity for the science camera in this mode can be found on the GRAVITY webpage and are based on a preliminary characterisation of the mode. Due to the need of good atmospheric conditions (turbulence class 30% and better), observations are strongly encouraged to be carried out in service mode to ensure that the conditions are met. Note that 'dual-field wide' mode only provides relative measures (differential visibilities and phases), no absolute visibilities, due to atmospheric effects when separation increases. Calibrations of the interferometric transfer function are thus not needed and not offered for this mode.
    
  • Starting with period P112 GRAVITY single-field and dual-field acquisition templates will each be split into two separate templates: on-axis and off-axis. More information on their use cases can be found in the GRAVITY User Manual.
  • For the GRAVITY dual-field wide mode at the limit of system performance, in particular for crowded fields or embedded objects, it is recommended to confirm positions and magnitudes of AO-guide and fringe tracking stars in images with sufficient angular resolution, not relying purely on catalogs. Such images might also be provided as additional finding charts. We are in the process of further characterizing the performance of the GRAVITY-wide mode as a function of separation of the FT star and the atmospheric conditions. Note that the offered maximum separation of 30 arcsec distance may be optimistic unless the weather is excellent and both the FT and SC stars are bright. With more typical conditions, the maximum separation may be somewhat smaller. A performance estimation tool for this mode is currently under development by the JMMC.
• MATISSE is offered on the UTs (supported by the visible GPAO AO system) and on all the ATs configurations in Service and Visitor modes.
  • The same applies for MATISSE in GRA4MAT mode, exception made fr the chopping on the UTs which is not offered.
  • As from P112, MATISSE is offered for narrow off-axis mode for exo-planet and similar observations (with GRAVITY as fringe tracker), meaning while GRAVITY tracks fringes on a source, MATISSE can point to a nearby offset position. See the MATISSE news page for details.
• PIONIER PIONIER is offered on all ATs configuration in both service and visitor mode. See the overview or overheads pages.
  • The cooling pump of the detector is currently not performing, and the temperature sensor of the detector is not functional. This situation may affects the performance of the instrument. While a spare for the pump has been identified, the temperature sensor problem remains. A direct consequence of the instrument status is that no Large nor Monitoring Programs are offered for Period 114.