GRAVITY Commissioning

First Commisioning

During the commissioning runs of GRAVITY at the VLTI between 2015 and 2018, selected astronomical targets were observed to demonstrate the capabilities of the instrument, find the best observing strategies and optimize the performance of the data reduction pipeline.

The collection and release of these datasets has been facilitated by the smooth operation of the instrument since its first observing night at the interferometer. They illustrate well the power of GRAVITY on different science targets. The data can be used as reference to plan future programmes and, in some cases, for scientific work. 

The GRAVITY commissioning data is packaged separately for each object and telescopes used (ATs or UTs). Follow the links to reach lists of data files divided by science and calibration. There are separate links to download the entire science/calibration data package or file-by-file. Files can then be selected in the usual way for Science Archive requests. In order to retrieve the calibration data for a given set of files, the CalSelector option can be specified on the Archive Request page. A set of pipeline recipes for reduction of GRAVITY data has been released.


GRAVITY Wide combines the dual-beam capabilities of the VLTI and the GRAVITY instrument to increase the maximum separation between the science target and the reference star from 2 arcseconds with the 8 m UTs up to several 10 arcseconds, limited only by the Earth's turbulent atmosphere. This increases the sky-coverage of GRAVITY by two orders of magnitude, opening up milliarcsecond resolution observations of faint objects, and in particular the extragalactic sky. GRAVITY Wide commissioning observations in 2019 - 2022 include first infrared interferometry of two redshift z∼2 quasars. The link to the paper describing the results is available here.


It is important to stress the limitations of these data. Some of the observations were taken with exploratory exposure times and with non-optimal observing strategies; the headers of some of the files may not be complete and homogeneous, since the commission runs were also used to check and optimize the header keywords.

Please also note that GRAVITY files are large, typically around 300Mbyte (compressed), so that download to the host computer can be lengthy for large requests. 


First Commissioning Targets

Eta Car


BP Cru (UTs)

BP Cru (ATs)

SS 433

PDS 456


Xi Tel

24 Cap

BD-12 501

CD-26 996

CD-35 1962


If any of these data are used for publication, please acknowledge that the results are based on public data released from the GRAVITY commissioning observations at the VLT Interferometer under Programme IDs 60.A-9102(A), 60.A-9102(B) and 60.A-9102(C) (First Commissioning) or 60.A-9102(I) (GRAVITY Wide).