|VLT Survey Telescope|
|Organization|| European Southern Observatory |
|Location||Paranal Observatory , Cerro Paranal , Atacama Desert , Chile|
|Optical resolution||0,216 s|
|Focal distance||14416 mm|
|Mounting type||ALT-AZ (Cassegrain)|
The VLT Survey Telescope ( VST ) was the last telescope to be added to the Paranal Observatory , belonging to the European Southern Observatory , in the Atacama desert of northern Chile . It is housed in an enclosure adjacent to the Very Large Telescope (VLT) with four telescopes located on top of Cerro Paranal . The VST is a highly-tracking telescope with a field of view equal to twice the width of the full Moon . It is the largest telescope in the world designed exclusively to scan the sky with visible light. [ 1 ]
The VST program is a collaboration between the Capodimonte Astronomical Observatory (OAC), Naples , Italy , and the European Southern Observatory (ESO) started in 1997. The OAC is one of the members of the Istituto Nazionale di Astrofísica (INAF), and It was he who created an independent institute for the coordination of the technological and scientific aspects of the project, called VST Centro a Napoli (VSTceN). VSTcen was founded and directed by Prof. Massimo Capaccioli from the VST project, and hosted at the OAC. ESO and VSTceN collaborated in the commissioning phase, while ESO was responsible for the civil engineering works and placing the dome on the site. [ 2] The telescope has started making observations and ESO is solely responsible for managing its operations and maintenance.
The VST Survey Telescope has a primary mirror of 2.65 meters in diameter, which began to be built in 2007 and was completed in 2011 at the Paranal Observatory , located in Chile . It has a field of view of one degree square (approximately four full moons ) and its main scientific function is to serve as a wide field of view instrument to explore the large-scale structure of the Universe (only visible from the southern hemisphere) , able to identify the most suitable candidates for detailed examination by the VLT [ 1 ]Together with its OmegaCAM camera, the VST is capable of high angular resolution (0.216 arcseconds / pixel), and is capable of independent search projects in the visible part of the spectrum. [ 3 ]
The telescope has two mirrors, a primary mirror (M1) and a smaller secondary mirror (M2), which reflect light from the sky to the OmegaCAM camera. Both mirrors are made from a crystalline ceramic material called Sitall , chosen for its low coefficient of thermal expansion . The VST primary mirror is the larger of the two, with a diameter of 265 cm and a thickness of 14 cm. The secondary mirror is less than half the size of the M1 with a diameter of only 93.8 cm and a thickness of 13 cm, [ 4 ] made with original VST optical components manufactured at the Lytkarino Glass Factory in Moscow , which were accepted in September 2001. [ 5 ]
A computer controlled system controls the position of the M1 and the position of the M2. This technology preserves the optical quality of the image by keeping the mirrors perfectly positioned at all times. The M1 is continually remodeled by a drive network of 84 axial motors distributed under the mirror surface and 24 radial motors dislocated laterally. Also in the cell of the primary mirror there is another instrument capable of modifying the optical configuration of the telescope by passing through a corrector made up of a double set of lenses, to an atmospheric dispersion corrector (ADC) made up of a set of counter-rotations of prisms. , capable of correcting the optical scattering phenomena due to the variation of the air mass induced by the change of the altitude angle. The secondary mirror is actively controlled by a deformable platform capable of tilting the mirror during exposure. The optical system also includes a front wave sensor, mounted under the primary mirror cell along with the local guidance system, capable of providing feedback for optical correction. These systems give the VST the ability to be autonomous in terms of orientation, tracking and control of the optics.
OmegaCAM: The VST Chamber
At its Cassegrain focus, the VST houses a Large Image Capacity Camera ( OmegaCAM ), comprising a mosaic of 32 2Kx4K CCDs (268 megapixels), and is produced by an international consortium between the Netherlands , Germany , Italy , and the THAT. [ 7 ]OmegaCAM design features include four auxiliary CCD cameras, two self-guided and two for online image analysis. Up to 12 filters can be used, ranging from ultraviolet to near infrared. The detector system operates in a vacuum at approximately -140 degrees Celsius behind a large window. This window not only protects the detectors from air and moisture, but also acts as an additional corrective lens. [ 8 ]
The VST's main function is to support the Very Large Telescope by providing scans, both of which have done extensive studies through multi-color imagery and more specific searches for rare astronomical objects. Three of them have already been planned as part of the Public Tracking Project , which is expected to take five years to complete. These include Kilo-Degree scans (KIDS), VST ATLAS, VST Hα photometric, and South Galactic Plane (VPHAS) scans. They will focus on a wide range of astronomical topics from searching for highly energetic quasars to understanding the nature of dark energy. [ 9 ]More information about the traces can be found on the official website of the European Southern Observatory :
The construction of the VST suffered several setbacks. The first primary mirror was destroyed in 2002 during its transfer from Europe to Chile. The M2 was also slightly damaged during transport, and had to be sent in for repair. Although a series of emergency measures were applied to solve these problems with minimal impact on the VST calendar, the telescope suffered delays. M2 was repaired and an M1 replica was built. [ 4 ] The test was completed in Italy and the telescope was disassembled, painted and filled, then shipped and assembled in Paranal. The first parts arrived in June 2007, and the first phase of integration in Paranal was completed in April 2008. [ 6 ]The first VST images were released on June 8 , 2011 . [ 1 ]
Science with VTS
In planetary science, the survey telescope aims to discover and study remote bodies of the solar system as trans-Neptunian objects, as well as the search for the transit of extrasolar planets. The galactic plane will also be studied extensively with the VST, which will seek to find traces of interactions in the Milky Way , and will provide astronomers with crucial data for understanding the structure and evolution of our galaxy. A little further afield, the VST will explore nearby galaxies, extragalactic and even planetary nebulae, and carry out faint object scans. The telescope will also scan the universedistant to help astronomers find answers to long-standing questions in cosmology. It will focus on supernovae to help pin down the cosmic distance scale and understand the expansion of the Universe. The VST will also look for cosmic structures in the active nuclei of galaxies and quasars to improve our understanding of galaxy formation and the early history of the Universe. [ 10 ]
Through the VST ATLAS scans, the telescope will target one of the most fundamental questions in astrophysics today: the nature of dark energy. The tracking aims to detect small amplitude oscillations known as 'baryon' ripples that can be detected in the potential spectrum of galaxies and that are the imprint of sound waves in the Universe early in the distribution of matter. The equation state of dark energy can be determined by measuring the characteristics of these oscillations. Extrapolating from previous scans, it is very likely that the VST will make some unexpected discoveries with important consequences for the current understanding of the Universe. [ 10 ]
First images of the VST
The first image taken by the VST (top left) shows the spectacular star-forming region of Messier 17, also known as the Omega Nebula or the Swan Nebula, which has never been seen before. This vast region of hot gas, dust, and young stars lies in the heart of the Milky Way , in the constellation Sagittarius (the Archer). The VST field of view is so large that the entire nebula, including its fainter outer parts, is captured and retains its extraordinary sharpness throughout the image. The data was processed with the Astro-WISE software system developed by EA Valentijn and collaborators in Groningen and elsewhere. [ 1 ]
The second image released by the VST (left) may be the best portrait of the globular cluster Omega Centauri ever made. Omega Centauri, in the constellation Centaurus (The Centaurus), is the largest globular cluster in the sky, but the very wide field of view of the VST and its powerful OmegaCAM camera can encompass even the faint outer regions of this spectacular object. The left region of the image includes about 300,000 stars. The data were processed using the VST-Tube system developed by A. Grado and collaborators from the INAF-Capodimonte Observatory. [ 1 ]
The third image released by the VST (right) shows a triplet of bright galaxies in the constellation Leo (The Lion), along with a multitude of fainter objects: the much narrower distant background galaxies and stars of the Milky Way. The image hints at the power of VST and OmegaCAM for surveying the extragalactic universe and for mapping low-brightness objects in the galactic halo. The image on the left is a composite created by combining exposures taken through three different filters. The light that passed through a near infrared filter was red, red light is green, and green light is magenta. [ 12 ]
- List of the largest optical reflector telescopes
- Very Large Telescope
- VISTA (telescope)
- Large Telescope for Synoptic Surveys
- "Images taken by the VLT Survey Telescope" . eso.org (in English) . THAT. July 28, 2011 . Retrieved August 30, 2014 .
- "VST Telescope" (in English) . THAT . Retrieved August 30, 2014 .
- Capaccioli, M., Mancini, D. and Sedmak, G.; Mancini; Sedmak (Junio de 2005). El VLT Survey Telescope: A Status Report (en inglés) 120. ESO. pp. 10-13. Bibcode:2005Msngr.120...10C.
- "The mirrors of the VST" (in English) . THAT . Retrieved August 30, 2014 .
- Capaccioli, M., Cappellaro, E., Mancini, D. and Sedmak, G. (2003). «El VLT Survey Telescope (VST) Project: a progress report». Mem. S.A.It. Suppl. (en inglés) (SAIt) 3 (286).
- "VSTceN Portal: VLT Survey Telescope at Naples Center Web Portal" (in English) . INAF. Archived from the original on March 5, 2007 . Retrieved August 30, 2014 .
- Cappellaro, E. (June 2005). "OmegaCAM: The VST Camera". Messenger ( ESO) 120 : 13. Bibcode : 2005Msngr.120 ... 13C .
- "The VST Camera" (in English) . THAT . Retrieved August 30, 2014 .
- "The VST traces" . THAT . Retrieved August 30, 2014 .
- "VST science" (in English) . THAT. Archived from the original on August 14, 2011 . Retrieved August 30, 2014 .
- "Image of the Carina Nebula marks inauguration of the VLT Survey Telescope" . ESO Press Release. December 6, 2012 . Retrieved August 30, 2014 .
- "VST looks at Leo's Triplet - and beyond" . THAT. July 27, 2011 . Retrieved August 30, 2014 .