The VISTA (Visible and Infrared Survey Telescope for Astronomy) is a wide-field

reflecting telescope A reflecting telescope (also called a reflector) is a telescope that uses a single or a combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century by Isaac Newton as an alternati ...

with a 4.1 metre mirror, located at the

Paranal Observatory Paranal Observatory is an astronomical observatory operated by the European Southern Observatory (ESO). It is located in the Atacama Desert of Northern Chile on Cerro Paranal at altitude, south of Antofagasta. By total light-collecting area, ...

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

. It is operated by the

European Southern Observatory The European Organisation for Astronomical Research in the Southern Hemisphere, commonly referred to as the European Southern Observatory (ESO), is an intergovernmental organization, intergovernmental research organisation made up of 16 m ...

and started science operations in December 2009. VISTA was conceived and developed by a consortium of universities in the United Kingdom led by

Queen Mary University of London Queen Mary University of London (QMUL, or informally QM, and formerly Queen Mary and Westfield College) is a public university, public research university in Mile End, East London, England. It is a member institution of the federal University ...

and became an

in-kind The term in kind (or in-kind) generally refers to goods, services, and transactions not involving money or not measured in monetary terms. It is a part of many spheres, mainly economics, finance, but also politics, work career, food, health and o ...

contribution to ESO as part of the UK's accession agreement, with the subscription paid by the UK

Science and Technology Facilities Council The Science and Technology Facilities Council (STFC) is a United Kingdom government agency that carries out research in science and engineering, and funds UK research in areas including particle physics, nuclear physics, space science and astr ...

(STFC). VISTA is a survey telescope working at

infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...

wavelengths, and is by far the largest telescope in the world dedicated to surveying the sky at near-infrared wavelengths. The telescope has only one instrument: VIRCAM, the Vista InfraRed CAMera. This is a 3-tonne camera containing 16 special detectors sensitive to infrared light, with a combined total of 67 million pixels. A second-generation instrument called 4MOST, a 2400-object fibre-fed multi-object

spectrograph An optical spectrometer (spectrophotometer, spectrograph or spectroscope) is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify mate ...

, is under development to start operations at the telescope in 2025. Observing at wavelengths longer than those visible to the human eye allows VISTA to study objects that may be almost impossible to see in visible light because they are cool, obscured by dust clouds or because their light has been stretched towards redder wavelengths by the expansion of space during the light's long journey from the early Universe.

The project

VISTA is carrying out surveys of the southern sky at near

wavelengths. Such surveys should both return direct scientific results and help select objects for further studies with larger telescopes. There are two related projects: the Wide Field Camera (WFCAM) on the United Kingdom Infrared Telescope in

Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...

carries out infrared surveys of the northern sky, and the

VLT Survey Telescope The VLT Survey Telescope (VST) is a telescope located at ESO's Paranal Observatory in the Atacama Desert of northern Chile. It is housed in an enclosure immediately adjacent to the four Very Large Telescope (VLT) Unit Telescopes on the summit of ...

carries out surveys of the southern sky in visible light. Fornax Cluster of Galaxies

The project was initiated in 1999 by the VISTA ConsortiumThe VISTA consortium consists of

Queen Mary, University of London Queen Mary University of London (QMUL, or informally QM, and formerly Queen Mary and Westfield College) is a public research university in Mile End, East London, England. It is a member institution of the federal University of London. Today, ...

as consortium leader,

Queen's University Belfast The Queen's University of Belfast, commonly known as Queen's University Belfast (; abbreviated Queen's or QUB), is a public research university in Belfast, Northern Ireland, United Kingdom. The university received its charter in 1845 as part of ...

University of Birmingham The University of Birmingham (informally Birmingham University) is a Public university, public research university in Birmingham, England. It received its royal charter in 1900 as a successor to Queen's College, Birmingham (founded in 1825 as ...

University of Cambridge The University of Cambridge is a Public university, public collegiate university, collegiate research university in Cambridge, England. Founded in 1209, the University of Cambridge is the List of oldest universities in continuous operation, wo ...

Cardiff University Cardiff University () is a public research university in Cardiff, Wales. It was established in 1883 as the University College of South Wales and Monmouthshire and became a founding college of the University of Wales in 1893. It was renamed Unive ...

University of Central Lancashire The University of Lancashire (previously abbreviated UCLan) is a public university based in the city of Preston, Lancashire, England. It has its roots in ''The Institution For The Diffusion Of Useful Knowledge'', founded in 1828. Previously k ...

Durham University Durham University (legally the University of Durham) is a collegiate university, collegiate public university, public research university in Durham, England, founded by an Act of Parliament (UK), Act of Parliament in 1832 and incorporated by r ...

University of Edinburgh The University of Edinburgh (, ; abbreviated as ''Edin.'' in Post-nominal letters, post-nominals) is a Public university, public research university based in Edinburgh, Scotland. Founded by the City of Edinburgh Council, town council under th ...

University of Hertfordshire The University of Hertfordshire (UH) is a Universities in the United Kingdom, university in Hertfordshire, United Kingdom. The university is based largely in Hatfield, Hertfordshire, Hatfield, Hertfordshire. Its antecedent institution, Hatfield ...

Keele University Keele University is a Public university#United Kingdom, public research university in Keele, approximately from Newcastle-under-Lyme, Staffordshire, England. Founded in 1949 as the University College of North Staffordshire, it was granted uni ...

University of Leicester The University of Leicester ( ) is a public university, public research university based in Leicester, England. The main campus is south of the city centre, adjacent to Victoria Park, Leicester, Victoria Park. The university's predecessor, Univ ...

Liverpool John Moores University Liverpool John Moores University (abbreviated LJMU) is a public university, public research university in the city of Liverpool, England. The university can trace its origins to the Liverpool Mechanics' School of Arts, established in 1823. This ...

University of Nottingham The University of Nottingham is a public research university in Nottingham, England. It was founded as University College Nottingham in 1881, and was granted a royal charter in 1948. Nottingham's main campus (University Park Campus, Nottingh ...

University of Oxford The University of Oxford is a collegiate university, collegiate research university in Oxford, England. There is evidence of teaching as early as 1096, making it the oldest university in the English-speaking world and the List of oldest un ...

University of St Andrews The University of St Andrews (, ; abbreviated as St And in post-nominals) is a public university in St Andrews, Scotland. It is the List of oldest universities in continuous operation, oldest of the four ancient universities of Scotland and, f ...

University of Southampton The University of Southampton (abbreviated as ''Soton'' in post-nominal letters) is a public university, public research university in Southampton, England. Southampton is a founding member of the Russell Group of research-intensive universit ...

University of Sussex The University of Sussex is a public university, public research university, research university located in Falmer, East Sussex, England. It lies mostly within the city boundaries of Brighton and Hove. Its large campus site is surrounded by the ...

, and

University College London University College London (Trade name, branded as UCL) is a Public university, public research university in London, England. It is a Member institutions of the University of London, member institution of the Federal university, federal Uni ...

. of 18 universities in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

(UK), which obtained funding from a joint infrastructure fund of the UK government and further funding from the

Particle Physics and Astronomy Research Council The Particle Physics and Astronomy Research Council (PPARC) was one of a number of research councils in the United Kingdom. It directed, coordinated and funded research in particle physics and astronomy for the people of the UK. Its head office w ...

. The project is valued at €46M (£36M). After considering several sites in

, the consortium chose the

of the

(ESO), namely a secondary peak 1,500 m from the

Very Large Telescope The Very Large Telescope (VLT) is an astronomical facility operated since 1998 by the European Southern Observatory, located on Cerro Paranal in the Atacama Desert of northern Chile. It consists of four individual telescopes, each equipped with ...

(VLT). The consortium selected the

UK Astronomy Technology Centre The UK Astronomy Technology Centre (UK ATC) is based at the Royal Observatory in Edinburgh, Scotland, and is part of the Science and Technology Facilities Council. The UK ATC designs, builds, develops, tests and manages major instrumentation ...

to take technical responsibility for design and construction of the telescope. Two years later – in 2002 – the UK joined ESO, and VISTA became an in-kind component of the joining fee. The consortium then completed the construction and commissioning of the telescope, and the

– on behalf of the UK – handed over the telescope to ESO, for the benefit of astronomers in all its member countries.

VISTA Surveys

The scientific goals of the VISTA surveys, which started in 2010, include many of the most exciting problems in astrophysics today, ranging from the nature of dark energy to the threat of near-Earth asteroids. There are six large public surveys being conducted by VISTA: UltraVISTA, VISTA Kilo-Degree Infrared Galaxy Survey (VIKING), VISTA Magellanic Survey (VMC)
VISTA Variables in the Via Lactea (VVV)
VISTA Hemisphere Survey (VHS), VISTA Deep Extragalactic Observations Survey (VIDEO). These will take up the majority of the observing time in the telescope's first five years of operations. The surveys cover different areas of sky to different depths to attack a wide range of scientific questions. More information about each of the VISTA surveys can be found on th

website and in th

webpage.

Science with VISTA

Because VISTA is a large telescope that also 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 ten times the area of the full Moon and it will be able to detect and catalogue objects over the whole southern sky with a sensitivity that is forty times greater than that achieved with earlier infrared sky surveys such as the highly successful Two Micron All-Sky Survey. This jump in observational power—comparable to the step in sensitivity from the unaided eye to Galileo's first telescope—will reveal vast numbers of new objects and allow the creation of far more complete inventories of rare and exotic objects in the southern sky. VISTA observations will support research in many astronomical areas. Within our galaxy, VISTA is expected to find many new brown dwarf stars and be able to test ideas about the nature of dark matter. One VISTA survey is designed to find and study huge numbers of variable stars in our galaxy by taking images of the same areas of sky at different times. Using VISTA data astronomers will be able to map the structure of our galaxy in much more detail than ever before. Another VISTA survey will study our neighbouring small galaxies, the Magellanic Clouds, and their surroundings. VISTA data will also be used to create a 3D map of about 5% of the entire observable Universe. Further out, VISTA will be a powerful tool for discovering remote quasars and studying the evolution of galaxies and clusters of galaxies. It will help to probe the nature of dark energy by finding very distant galaxy clusters.

Infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...

measurements from the VVV astronomical survey have been employed to bolster the

cosmic distance ladder The cosmic distance ladder (also known as the extragalactic distance scale) is the succession of methods by which astronomers determine the distances to celestial objects. A ''direct'' distance measurement of an astronomical object is possible ...

, namely by providing reliable distances to

star clusters A star cluster is a group of stars held together by self-gravitation. Two main types of star clusters can be distinguished: globular clusters, tight groups of ten thousand to millions of old stars which are gravitationally bound; and open cluste ...

and

Cepheid A Cepheid variable () is a type of variable star that pulsates radially, varying in both diameter and temperature. It changes in brightness, with a well-defined stable period (typically 1–100 days) and amplitude. Cepheids are important cosmi ...

variable stars A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes systematically with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are ...

.Majaess, Daniel; Turner, David; Moni Bidin, Christian; Mauro, Francesco; Geisler, Douglas; Gieren, Wolfgang; Minniti, Dante; Chené, André-Nicolas; Lucas, Philip; Borissova, Jura; Kurtev, Radostn; Dékány, Istvan; Saito, Roberto K. (2011)
"New Evidence Supporting Membership for TW Nor in Lyngå 6 and the Centaurus Spiral Arm"
''The Astrophysical Journal Letters'', Volume 741, Issue 2, article id. L27, 2, via SAO/NASA Astrophysics Data System (ADS).Majaess, D.; Turner, D.; Moni Bidin, C.; Geisler, D.; Borissova, J.; Minniti, D.; Bonatto, C.; Gieren, W.; Carraro, G.; Kurtev, R.; Mauro, F.; Chené, A.-N.; Forbes, D.; Lucas, P.; Dékány, I.; Saito, R. K.; Soto, M. (2012)
"Strengthening the open cluster distance scale via VVV photometry"
''Astronomy & Astrophysics'', 537, via SAO/NASA Astrophysics Data System (ADS).

Selection of VISTA Images

The first released image (left) shows the Flame Nebula (NGC 2024), a spectacular star-forming cloud of gas and dust in the familiar constellation of Orion (the Hunter) and its surroundings. In visible light the core of the object is hidden behind thick clouds of dust, but the VISTA image, taken at infrared wavelengths, can penetrate the murk and reveal the cluster of hot young stars hidden within. The wide field of view of the VISTA camera also captures the glow of NGC 2023 and the ghostly form of the famous Horsehead Nebula. Other stunning nebula images include the VISTA views of the

Orion Nebula The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a diffuse nebula in the Milky Way situated south of Orion's Belt in the Orion (constellation), constellation of Orion, and is known as the middle "star" in the "sword" of Orion. It ...

and the Lagoon Nebula. The picture on the right is a wide-field view of the Orion Nebula (Messier 42), lying about 1350 light-years from Earth, taken with the VISTA infrared survey telescope at ESO's Paranal Observatory in Chile. The telescope's huge field of view allows the whole nebula and its surroundings to be imaged in a single picture and its infrared vision also means that it can peer deep into the normally hidden dusty regions and reveal the curious antics of the very active young stars buried there. An image of the "Blue Lagoon" is seen on the left (below the Flame Nebula picture) — it is an infrared image taken as part of the VVV survey. It shows the stellar nursery called the Lagoon Nebula (also known as Messier 8), which lies about 4000–5000 light-years away in the constellation of Sagittarius (the Archer). VISTA can also stare far beyond our galaxy. In the example on the left (below the image of the Orion Nebula) the telescope took a family photograph of a cluster of galaxies in the constellation of Fornax (the Chemical Furnace). The wide field allows many galaxies to be captured in a single image including the striking barred-spiral NGC 1365 and the big elliptical galaxy NGC 1399. The image was constructed from images taken through Z, J and Ks filters in the near-infrared part of the spectrum and has captured many of the cluster members in a single image. At the lower-right is the elegant barred-spiral galaxy NGC 1365 and to the left the big elliptical NGC 1399, surrounded by a swarm of faint globular clusters. The image is about 1 degree by 1.5 degrees in extent and the total exposure time was 25 minutes.

Technical details

Telescope design

The objective to repeatedly image large areas of sky at seeing-limited resolution led to a unique optical design. The primary mirror is a

concave Concave or concavity may refer to: Science and technology * Concave lens * Concave mirror Mathematics * Concave function, the negative of a convex function * Concave polygon A simple polygon that is not convex is called concave, non-convex or ...

hyperboloid In geometry, a hyperboloid of revolution, sometimes called a circular hyperboloid, is the surface generated by rotating a hyperbola around one of its principal axes. A hyperboloid is the surface obtained from a hyperboloid of revolution by def ...

with 4.1 m diameter and about f/1

focal ratio An f-number is a measure of the light-gathering ability of an optical system such as a camera lens. It is calculated by dividing the system's focal length by the diameter of the entrance pupil ("clear aperture").Smith, Warren ''Modern Optical ...

. The mirror has a meniscus shape of 17 cm thickness with a central 1.2 m hole to accommodate the camera at the Cassegrain focus. It was cast from Zerodur by Schott in

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

and subsequently polished and figured by LZOS,

Moscow Moscow is the Capital city, capital and List of cities and towns in Russia by population, largest city of Russia, standing on the Moskva (river), Moskva River in Central Russia. It has a population estimated at over 13 million residents with ...

. It is the largest mirror of this shape and of such short focal ratio; polishing it took 2 years, which was longer than anticipated.Emerson, J., McPherson, A., Sutherland, W. (2006)
Visible and Infrared Survey Telescope for Astronomy: Progress report
''The Messenger'', 126. p.41. The mirror is supported by a number of

actuators An actuator is a component of a machine that produces force, torque, or displacement, when an electrical, pneumatic or hydraulic input is supplied to it in a system (called an actuating system). The effect is usually produced in a controlled way. ...

(81 on the back and 24 around the edge), which allow its shape to be controlled by computers. The secondary mirror is a

convex Convex or convexity may refer to: Science and technology * Convex lens, in optics Mathematics * Convex set, containing the whole line segment that joins points ** Convex polygon, a polygon which encloses a convex set of points ** Convex polytop ...

hyperboloid of 1.24 m diameter. The combination of the two hyperbolic mirrors makes this a quasi- Ritchey-Chrétien design. The combined focal ratio is about f/3, but the image quality of the two mirrors alone would be poor. The secondary mirror is mounted on a hexapod support so that its position, tip, and tilt are also computer-controlled. The infrared camera was built by a consortium composed of the Rutherford Appleton Laboratory, the

, and

, and is the world's largest at almost three tonnes. Telescope and camera form a single optical design, as the three field correction lenses in the camera are essential for the projection of a focussed image of the sky on the detectors. For an infrared camera, it is also vital to block heat radiation from the telescope and dome. This is accomplished by a sequence of cooled baffles in front of the field corrector lenses. Also, the secondary mirror is undersized to avoid edge detectors viewing warm structure outside the edge of the primary; this means the

aperture In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image o ...

seen by any point in the image plane is 3.7 m. This design requires the camera's vacuum

cryostat A cryostat (from ''cryo'' meaning cold and ''stat'' meaning stable) is a device used to maintain low cryogenic temperatures of samples or devices mounted within the cryostat. Low temperatures may be maintained within a cryostat by using various ...

– which cools the detectors as well as the baffles – to be more than 2 m long, with a front window of 95 cm diameter. A filter wheel just in front of the detectors allows the selection of a particular infrared wavelength range.Emerson, J.P., Sutherland, W.J., McPherson, A.M., Craig, S.C., Dalton, G.B., Ward, A.K. (2005)
The Visible & Infrared Survey Telescope for Astronomy
''The Messenger'', 117. p.27 Over an area corresponding to 1.65° diameter on the sky, the image plane has 16 arrays of infrared detectors, each array with 2048x2048 pixels of 20 μm size, corresponding on average to 0.34" on the sky. The focal length of 12.1 m combines with the baffled aperture of 3.7 m to a focal ratio of 3.26. The arrays are separated by 90% of their width in one direction and by just under 50% their width in the other direction. A single exposure therefore corresponds to a patchy "paw print" on the sky. To fill the gaps and obtain a conventional image at least six shifted paw prints have to be combined into a "tile", which then is 1.5° by 1.0°. The image plane of the camera also has

wave front In physics, the wavefront of a time-varying ''wave field'' is the set ( locus) of all points having the same '' phase''. The term is generally meaningful only for fields that, at each point, vary sinusoidally in time with a single temporal freq ...

detectors used to control the shape of the primary mirror and the position and tip/tilt of the secondary mirror ( active optics). This compensates for flexure and ensures a focused image at all

altitudes Altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The exact definition and reference datum varies according to the context (e.g., aviation, geometry, geographical s ...

. The hilltop where VISTA is located was flattened to erect the enclosure building and an auxiliary building. The auxiliary building includes facilities to wash, strip, and coat the primary mirror. The coating can be in aluminium, or normally in protected silver for better infrared performance. The fixed base of the enclosure supports the rotating steel dome. Two sliding doors form the dome slit. Further dome panels can be opened to increase ventilation, and a wind shield can be deployed to close parts of the slit. During the day, the dome is kept at night-time temperature.Craig, S.C., McPherson, A. (2003).
VISTA project overview
".

. Retrieved 23 September 2009.

Operation and data flow

VISTA infrared mosaic of the central Milky Way

On completion, the telescope was handed over to ESO, which has selected six public surveys for VISTA, taking up 75% of the available observing time. Proprietary surveys to occupy the remaining time are proposed to ESO, which will schedule approved proposals for observation.VISTA web site
/ref> The observations are carried out by operators at the

, remotely from the VLT control building. The combination of the large detector array and the short and frequent exposures necessary at infrared wavelengths results in a high data rate of 200–300 GB per night. A quick-look reduction at the Paranal Observatory will be used for daily quality control, but the principal data flow is to transfer the raw data to ESO headquarters in Garching near Munich,

, for ingestion into the data archive. Users can extract paw prints (see above) and pass them through a calibration pipeline to remove instrumental artefacts and calibrate the astrometry and photometry. The archive data will also be copied to the VISTA Data Flow System in the UK, where the paw prints will be combined into tiles (see above) and where source catalogues will be prepared from these.

Notes and references

External links

VISTA web site

at the

ESO VISTA page
{{Portal bar, Stars, Spaceflight, Solar System, Science European Southern Observatory Science and Technology Facilities Council Astronomical observatories in Chile Infrared telescopes