The Very Large Telescope Interferometer

The Very Large Telescope Interferometer (VLTI) consists in the coherent combination of the four VLT Unit Telescopes and of the four moveable 1.8m Auxiliary Telescopes. The VLTI provides milli-arcsec angular resolution in the near and mid infrared wavelength regime for low and intermediate (R=12000) spectral resolution.

General Description

The four 8.2-m Unit Telescopes (UTs) and the four 1.8-m Auxiliary Telescopes (ATs) constitute the light collecting elements of the VLTI. The UTs are set on fixed locations while the ATs can be relocated on 30 different stations. See the VLTI user manual for the currently offered AT stations. The telescopes can be combined in groups of three (triplet) or four (quadruplet) depending on the beam-combining instrument. After the light beams have passed through a complex system of mirrors and light paths have been equalized by the delay lines, the combination at near-infrared is performed by the instruments AMBER or PIONIER.

Due to its characteristics, the VLTI has become a very attractive means for scientific research on various objects like young pre-main sequence stars and their protoplanetary disks, post-main sequence mass-losing stars, binary objects and their orbits, solar system asteroids, and extragalactic objects such as active galactic nuclei.


28/08/2014: IMPORTANT according to the P95 Call For Proposal "Starting in March 2015 and during Period 95, the laboratory will undergo major modifica- tions in view of the arrival of the 2nd generation instruments GRAVITY and MATISSE as well as ESPRESSO, which will go in the nearby combined-coud ́e laboratory. As a conse- quence, MIDI will be decommissioned in March 2015, during Period 94, and AMBER and the Visitor Instrument, PIONIER, are not offered in Period 95. AMBER and PIONIER will be offered again in Period 96. "

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