 | Very Large Telescope: Encyclopedia II - Very Large Telescope - General information
Very Large Telescope - General information
The VLT consists of a cluster of four large (8.2 meter diameter) telescopes, and an interferometer (VLTI) which is used to resolve fine features. The interferometer will include a set of 1.8 meter diameter telescopes dedicated to interferometric observations. The 8.2 meter telescopes have been named after the names of some astronomical objects in the local Mapuche language: Antu (The Sun), Kueyen (The Moon), Melipal (The Southern Cross), and Yepun (Venus).
The VLT 8.2 meter telescopes can be operated in three modes:
- as a set of 4 independent telescopes (this is the primary mode of operation)
- as a single large incoherent instrument, for extra light-gathering capacity (this mode has now been abandoned, although multiple telescopes are sometimes independently pointed at the same object, either to increase the total light-gathering power, or to provide simultaneous observations with complementary instruments)
- as a single large coherent interferometric instrument (the VLT Interferometer or VLTI), for extra resolution (this is occasionally used, usually for observations of relatively bright sources).
The VLTs are equipped with a large set of instruments permitting observations to be performed from the near-UV to the mid-IR (ie a large fraction of the light wavelengths accessible from the surface of the Earth), with the full range of techniques including high-resolution spectroscopy, multi-object spectroscopy, imaging, and high-resolution imaging. In particular, the VLT has several Adaptive optics systems, which at infrared wavelengths correct for the effects of the atmospheric turbulence, providing images almost as sharp as if the telescope was in space. In the near-IR, the Adaptive Optics images of the VLT are up to 3 times sharper than those of the HST, and the spectroscopic resolution is many times better than Hubble.
The principle role of the main VLT telescopes is to operate as four independent telescopes. The interferometry (combining light from multiple telescopes) is used about 20% of the time for very high-resolution on bright objects.
Additionally, the four 8.2m telescopes are accompanied by 4 smaller Auxiliary Telescopes of 1.8 m each (2 operational in 2005, the other 2 in 2006), which can be placed on different positions around the four big telescopes in order to provide better interferometric observations.
The VLT is operated by the European Southern Observatory.
In 2005, VLT telescopes produced some of the first infrared images of extrasolar planets GQ Lupi b and 2M1207b.
Other related archives2004, 2005, 2M1207b, Adaptive optics, Atacama desert, C, CHARA array, Cerro Paranal, Chile, ESO, European Southern Observatory, GQ Lupi b, Giant Magellan Telescope, HST, List of astronomical interferometers at visible and infrared wavelengths, List of observatories, List of optical telescopes, Mapuche, Moon, Navy Prototype Optical Interferometer, Overwhelmingly Large Telescope, Paranal Observatory, Southern Cross, Sun, Venus, Wikipedia Project: Telescopes, active galactic nucleii, adaptive optics, angular resolution, arcsecond, closure-phase, delay lines, extrasolar planets, infrared, interferometer, interferometric, light wavelengths accessible from the surface of the Earth, optical telescopes, surface brightness, wavelength, µm
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