VLTI/GRAVITY Wide Science Verification with the Auxiliary Telescopes and Unit Telescopes

Deadline for submitting proposals via ESO's Phase 1 tool: 25 March 2022, 12:00 CET

text of the call

Accepted Programmes

Prog ID PI title Priority status data link
110.23T9 P.-O. Petrucci   The swan song: scrutinizing a microquasar at mas scale during its way to quiescence
110.241T I. Waisberg The closest look at the progenitor of the next Galactic type Ibc supernova High    
110.245D P. Mroz Measuring exoplanet mass and verifying free-floating planets by interferometric follow up of microlensing events High    
110.245B A. Mérand Confirming a promising microlensing stellar-mass black hole candidate by interferometric follow up High    


Starting with P110 (observtions starting in Oct 2022), GRAVITY dual-feed wide will be offered. This mode allows fringe tracking from a target that from 2" to 30” away from the science target by using the VLTI Star Separators to separate the beams. This modes will enable new exciting science by allowing observations of objects which were too faint for fringe tracking, and without a close (<2") fringe tracker source. GRAVITY-wide can only deliver spectrally differential observables at the moment (visibilities, phases and closure phases). As no absolute calibration is currently possible, observations with GRAVITY-Wide are simply made of a single SCI OBs.

We recall here the main performance and limitations for the 10% and 30% best atmospheric turbulence conditions (T). GRAVITY Wide is not offered for worst atmospheric conditions.

    T<10% T<30%
UTs Fringe Tracker
K<10.5 K<10.0
Spectrograph K~17.0 (H<17) K~16.0 (H<17)
ATs Fringe Tracker K<9.5 K<9.0
Spectrograph K~14 (H<14)
K~13 (H<14)

The magnitude limits of the fringe tracker (in K-band) and acquisition camera (in H-band) and the expected sensitivity for the science camera (in K-band).

The current Science Verification time is for 2 nights:

  • 1n on ATs around June 13th 2022: we will use the astrometric configuration (A0-G1-J2-K0) with baselines up to ~130m.
  • 1n on UTs around June 16th 2022: only using the MACAO visible adaptive optics

GTO protected targets

The list of protected targets for the GRAVITY Guaranteed Time Observations is available for P109 and P110. Observations of targets protected by the GRAVITY GTO will not be accepted for SV.

WARNING: all (raw) data and calibrations are public immediately after the observations. There is no proprietary period nor earlier data release to the PIs. See the VLT Science Verification Policy and Procedures for more details.

Science Verification Team

  • Antoine Mérand (ESO, Lead)
  • Enrique Garcia (ESO)
  • Xavier Haubois (ESO)
  • Sebastian Hoenig (GRAVITY)
  • Mathew Horrobin (GRAVITY)
  • Christian Hummel (ESO)
  • Heidi Korhonen (ESO)
  • Aaron Labdon (ESO)
  • Linda Schmidtobreick (ESO)
  • Taro Shimizu (GRAVITY)
  • Konrad Tristram (ESO)
  • Markus Wittkowski (ESO)
  • Julien Woillez (ESO)


  • February 2022: call issued
  • March 25th, 2022: deadline to submit the proposals
  • May 6, 2022: Proposers informed about the outcome
  • May 20, 2022: Deadline for Phase 2 Material for SV
  • June 15th and 19th 2022: GRAVITY Wide Science Verification observations start


The GRAVITY data reduction pipeline was released. Instructions for installing and running the pipeline can be found here:


Note this version is preliminary and has not been fully verified. If you notice unexpected behaviour, please consult the "Bug Reports" section of the page. GRAVITY Collaboration http://www.eso.org/sci/software/pipelines/gravity/

Citation Policy

Publications based on SV data obtained with the GRAVITY instrument should quote the following reference paper: GRAVITY Collaboration 10.1051/0004-6361/201730838

General Information

An integral part of the commissioning of a new instrument at the VLT is the Science Verification phase. SV programmes include a set of typical scientific observations that should verify and demonstrate to the community the capabilities of the new instrument in the operational framework of the VLT Observatory. See the SV Policy and Procedures: http://www.eso.org/sci/activities/vltsv/svdoc.pdf

Accepted Proposals

Prog. ID