GRAVITY is an interferometric instrument operating in the K band, between 2.0 and 2.4 μm. It combines 4 telescope beams and is designed to peform both interferometric imaging and astrometry by phase referencing. The instrument delivers spectrally dispersed interferometric quantities in low, medium, and high spectral resolution. GRAVITY's angular resolution is set by the maximum separation of the employed telescopes and the field of view of the instrument. In imaging mode, GRAVITY is able to resolve features between 4 mas (milli-arcsecond) and 50 mas with the UTs, and between 2 mas and 140 mas with the ATs. The astrometric accuracy is also given by the maximum separation of the telescopes and will be of the order of few 10 to 100 µas. GRAVITY is equipped with a dedicated fringe tracking subsystem and with a dedicated IR wavefront sensing system (CIAO) on the UTs.
GRAVITY is still being commissioned and the characterisation of the instrument is preliminary. The complete pre-requisites for GRAVITY service mode observations and the up-to-date magnitude limits can be found on the instrument description page and the GRAVITY Science Verification page.
Publications based on data obtained with the Gravity instrument should quote the following reference paper: Gravity Collaboration 2017, A&A, 602, 94.
- Questions related to service mode observations and proposal preparation should be addressed to the User Support Department.
- Questions related to visitor mode observations should be addressed to Paranal Science Operations (note that GRAVITY is currently offered only in service mode, except for GTO programmes).
- For VLTI users needing assistance to prepare their VLTI proposals, the community supported VLTI Expertise Centres - distributed throughout Europe - can offer in-depth support. They also offer support for observation preparation, advanced data reduction and interpretation.
- Please send us your comments, suggestions and report errors and inaccurate statements in the web pages and manuals.
Content of these pages
The following items are available on all the GRAVITY pages, using the bar on the left.
- Overview: a short description of the instrument
- News: list of changes affecting the instrument and/or its pages
- Instrument Description: all the important parameters of the instrument
- Manuals: links to all the documents related to GRAVITY
- Tools: a collection of useful tools and information for preparing and analysing GRAVITY observations
- Instrument Operations Team
- Visitor Instructions: Instrument specific instructions for Visiting Astronomers
- Science: links to scientific publications made with GRAVITY