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Inside the VLT. Credit: Y. Beletsky (LCO)/ESO The — The World’s Most Advanced Visible-light Astronomical Observatory

The Very Large Telescope array (VLT) is The VLT instrumentation programme is including the first image of an , the flagship facility for European visible- the most ambitious ever conceived for tracking individual moving around light . It is the world’s most a single observatory. It includes wide-field the at the centre advanced , consisting imagers, adaptive--corrected cam- of the , and observing the of four Unit with main eras and spectrographs, as well as high afterglow of the furthest known gamma- 8.2 metres in diameter and four movable resolution and multi-object spectrographs ray burst. 1.8-metre Auxiliary Telescopes. The VLT and covers a broad spectral region, from is sited on in northern (300 nm) to mid- (20 μm) Although the four 8.2-metre Unit Tele- at an of 2635 metres. . The 8.2-metre telescopes scopes can be combined in the VLTI, are housed in compact, thermally con- they are mostly used for individual obser- The telescopes can work together to trolled buildings, which rotate synchro- vations and are only available for inter­ form the giant VLT Interferometer (VLTI), nously with the telescopes. This design ferometric for a limited num- allowing to see details up minimises any adverse effects on the ber of nights every year. But the four to 25 times finer than with the individual observing conditions, for instance, from smaller, dedicated Auxiliary Telescopes telescopes. The light beams are com- air turbulence in the telescope tube, which (ATs) are available to allow the VLTI to bined in the VLTI using a complex system might otherwise occur due to variations operate every night. The ATs are mounted of mirrors in underground tunnels where in temperature and flow. The first of on tracks and can be moved between the light paths must be kept equal to the Unit Telescopes, Antu, began routine precisely defined observing positions from ­distances of less than one thousandth of scientific operations on 1 April 1999. where the beams of collected light are a millimetre over a hundred metres. With Today, all four Unit Telescopes and all four combined in the VLTI. this kind of precision the VLTI can recon- Auxiliary Telescopes are operational. struct images with an The ATs are very unusual telescopes, as of milliarcseconds, equivalent to distin- The VLT has made a major impact on they are self-contained in their ultra-­ guishing the two headlights of a car at the . It is the most compact protective domes, and travel with distance of the . productive individual ground-based their own electronics, ventilation, hydrau- ­facility, and results from the VLT have led lics and cooling systems. Each AT has The 8.2-metre Unit Telescopes can also to the publication of an average of more a transporter that lifts the telescope and be used individually to obtain images than one peer-reviewed scientific paper moves it from one position to the other. of celestial objects in one-hour exposures per day. The VLT contributes greatly to that are four billion times fainter than making ESO the most productive ground- The VLT hotel, the Residencia, is an those visible to the . based observatory in the world. The VLT award-winning building, and served as has stimulated a new age of discoveries, a backdrop for part of the James Bond with several notable scientific firsts, movie . Credit: ESO/B. Tafreshi (twanight.org) Tafreshi ESO/B. Credit:

This panoramic photograph captures the ESO Very Large Telescope (VLT) against a beautiful twilight on Cerro Paranal. The enclosures of the VLT stand out in the picture as the telescopes in them are readied for a night of studying the Universe. The VLT is the world’s most powerful advanced , consisting of four Unit Telescopes with primary mirrors 8.2 metres in diameter and four movable 1.8-metre Auxiliary Telescopes, which can be seen in the left corner of the image.

About ESO ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, , the , Poland, Portugal, Spain, Sweden, Switzerland and the , along with the host country of Chile.

ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO plays also a leading role in promoting and organising cooperation in astronomical research. ESO operates facilities at three unique world-class observing sites in the region of Chile: La Silla, Paranal and Chajnantor.

ESO education and Public Outreach Department Tel. +49 89 320 060 Karl-Schwarzschild-Straße 2 Fax +49 89 320 2362 85748 Garching bei München E-mail [email protected] Germany www.eso.org