The ESO Very Large Telescope incorporates an array of four 8.2-metre Unit Telescopes (UTs) which can work in single or in combined mode. In the latter, the VLT provides the total light collecting power of a 16-metre single telescope. The telescopes may also be used in interferometric mode providing high-resolution imaging. The useful wavelength range extends from the near UV (near 300 nm) up to the mid-infrared (about 25 microns).
The Unit Telescopes are equipped with active optics. The optical quality of the image is continually monitored by an image analyser using a reference star and the contributions of the various optical aberrations (defocus, astigmatism, coma, etc.) are computed.
Each UT is equipped with 4 foci where instruments can be placed. The VLT has an arsenal of 11 instruments, allowing astronomers to perform many different kind of observations. In addition, there are 2 instruments for interferometric observations. Second-generation instruments are currently being developed.
Unit Telescopes
The Names of the Unit Telescopes
The Unit Telescopes were given names from the indigenous Mapuche language:
Antu (UT1; The Sun)
Kueyen (UT2; The Moon)
Melipal (UT3; The Southern Cross)
Yepun (UT4; Venus – or ‘evening star’)
ATs
Control Room
