Physics Today: VISTA, the Visible and Infrared Survey Telescope for Astronomy, has officially gone operational. Jim Emerson, one of the VISTA project leaders said, “history has shown us some of the most exciting results that come out of projects like VISTA are the ones you least expect—and I’m personally very excited to see what these will be.”
VISTA is a survey telescope working at infrared wavelengths and is the world’s largest telescope dedicated to mapping the sky. At the heart of VISTA is a 3-ton camera containing 16 detectors sensitive to infrared light, with a combined total area of 67 million pixels.To avoid swamping the faint infrared radiation coming from space, the camera is cooled to -200 °C and is sealed with the largest infrared-transparent window ever made.The first image to be released publicly (see right) shows a 14-minute exposure of the star-forming region known as the Flame Nebula, or NGC 2024, in the constellation of Orion. At optical wavelengths, the object is hidden by giant dust clouds. VISTA, which works at infrared wavelengths can see through the dust at the cluster of very young stars at the object’s heart.The wide-field VISTA view also includes the glow of the reflection nebula NGC 2023, just below center, and the ghostly outline of the Horsehead Nebula (Barnard 33) towards the lower right.The bright bluish star towards the right is one of the three bright stars forming the Belt of Orion.Its large mirror, wide field of view, and very sensitive detectors will reveal a completely new view of the southern sky. Location, location, location The telescope is based near the European Southern Observatory‘s Very Large Telescope (VLT) in Paranal, Chile, an ideal spot for carrying out infrared observations due to the low water content of the atmosphere—water absorbs most infrared light—and the high altitude of 2635 meters above sea level—which limits the amount of atmospheric turbulence that can effect the air above the telescope.VISTA’s main mirror is 4.1 meters across and is the most highly curved mirror of this size and quality ever made—its deviations from a perfect surface are less than a few thousandths of the thickness of a human hair.Because VISTA has a large field of view it can both detect faint sources and also cover wide areas of sky quickly. Each VISTA image captures a section of sky covering about 10 times the area of the full Moon and it will be able to detect and catalog objects over the whole southern sky with a sensitivity that is 40 times greater than that achieved with earlier infrared sky surveys such as the Two Micron All-Sky Survey.VISTA was originally conceived and developed by a consortium of 18 universities in the United Kingdom led by Queen Mary, University of London. When the UK joined ESO, VISTA was offered to the organization as an in-kind contribution as part of the UK’s accession agreement.ESO formally took over VISTA on 10 December 2009 at a ceremony at ESO’s headquarters in Garching, Germany."VISTA is a unique addition to ESO’s observatory on Cerro Paranal. It will play a pioneering role in surveying the southern sky at infrared wavelengths and will find many interesting targets for further study by the Very Large Telescope, ALMA, and the future European Extremely Large Telescope,” says ESO Director General Tim de Zeeuw.VISTA will spend almost all of its time mapping the southern sky in a systematic fashion. The telescope is embarking on six major sky surveys with different scientific goals over its first five years.One survey will cover the entire southern sky and others will be dedicated to smaller regions to be studied in greater detail. VISTA’s surveys will help our understanding of the nature, distribution, and origin of known types of stars and galaxies, map the three-dimensional structure of our galaxy and the neighboring Magellanic Clouds, and help determine the relation between the structure of the universe and dark energy and dark matter.Paul Guinnessy
