The VLTI Commissioning Instrument

VINCI was a special test instrument installed on ESO's Very Large Telescope Interferometer (VLTI) at the Paranal Observatory. It was used during the first light and subsequent test phase of the VLTI, when light from celestial objects hit the telescopes for the first time.

The VLTI is a complex system. To ensure that the many devices involved worked properly together and could produce meaningful data, the VLTI went through a period of extensive testing and verification. This testing period included using VINCI to capture the very first light the telescopes saw, before the arrival of the official instruments AMBER and MIDI.

VINCI was able to combine the light of two of the eight telescopes comprising the VLT and accurately measure the obtained interference fringes. The main components of this high-tech instrument are aptly named MONA, a system that combines the light beams from two telescopes by means of optical fibres, and LISA, the infrared camera.

On 17 March 2001, the VLT Interferometer was used for the first time to carry out an astronomical observation, using siderostats — a type of heliostat designed to follow stars — instead of telescopes for this test. The target was Sirius (Alpha Canis Majoris), which is the brightest star in the sky, although it is in reality a binary star system.

Andreas Glindemann, head of the VLTI programme at the time, commented: “The tension was intense when starlight was guided for the first time from the primary mirror of the siderostats, through the light ducts, the tunnel and the beam combination laboratory to the detector of VINCI. And, after a few nights, the result was spectacular. The very first result, the fringe pattern of Sirius... This was a joyful moment and the champagne corks were popping.

With the success of the VLTI and VINCI, European astronomers were able to tune the VLTI to the highest possible performance and kick-start the world's most powerful optical/infrared interferometric facility, beginning a new era of exciting science and technology.


The authoritative technical specifications as offered for astronomical observations are available from the Science Operations page.

Location: Paranal (now decommissioned)
Telescope: Very Large Telescope Interferometer
Focus: N/A
Type: Infrared
Wavelength coverage: 2–2.5 µm
Spatial resolution: 2 mas
Spectral resolution:  
First light: 2001
Science goal:
  • To record light during the first light and subsequent test phase of the VLTI, ensuring the VLTI is tuned to the highest possible performance
Images taken with the instrument: Link
Images of the instrument: Link
Videos of the instrument: Link
Press Releases with the instrument: Link
Data papers:


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