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96-557: The Rubin Observatory will house the Simonyi Survey Telescope , a wide-field reflecting telescope with an 8.4-meter primary mirror that will photograph the entire available sky every few nights. The telescope uses a novel three-mirror design, a variant of three-mirror anastigmat , which allows a compact telescope to deliver sharp images over a very wide 3.5-degree diameter field of view. Images will be recorded by

192-484: A coudé train , diverting the light to a fixed position to such an instrument housed on or below the observing floor (and usually built as an unmoving integral part of the observatory building) was the only option. The 60-inch Hale telescope (1.5 m), Hooker Telescope , 200-inch Hale Telescope , Shane Telescope , and Harlan J. Smith Telescope all were built with coudé foci instrumentation. The development of echelle spectrometers allowed high-resolution spectroscopy with

288-476: A spherical or parabolic shape. A thin layer of aluminum is vacuum deposited onto the mirror, forming a highly reflective first surface mirror . Some telescopes use primary mirrors which are made differently. Molten glass is rotated to make its surface paraboloidal, and is kept rotating while it cools and solidifies. (See Rotating furnace .) The resulting mirror shape approximates a desired paraboloid shape that requires minimal grinding and polishing to reach

384-538: A 3.2-gigapixel charge coupled device imaging (CCD) camera, the largest digital camera ever constructed. The LSST was proposed in 2001, and construction of the mirror began (with private funds) in 2007. LSST then became the top-ranked large ground-based project in the 2010 Astrophysics Decadal Survey , and the project officially began construction 1 August 2014 when the United States National Science Foundation (NSF) authorized

480-423: A concave bronze mirror in 1616, but said it did not produce a satisfactory image. The potential advantages of using parabolic mirrors , primarily reduction of spherical aberration with no chromatic aberration , led to many proposed designs for reflecting telescopes. The most notable being James Gregory , who published an innovative design for a ‘reflecting’ telescope in 1663. It would be ten years (1673), before

576-455: A corrector plate) as primary optical elements, mainly used for wide-field imaging without spherical aberration. The late 20th century has seen the development of adaptive optics and lucky imaging to overcome the problems of seeing , and reflecting telescopes are ubiquitous on space telescopes and many types of spacecraft imaging devices. A curved primary mirror is the reflector telescope's basic optical element that creates an image at

672-402: A different meridional path. Stevick-Paul telescopes are off-axis versions of Paul 3-mirror systems with an added flat diagonal mirror. A convex secondary mirror is placed just to the side of the light entering the telescope, and positioned afocally so as to send parallel light on to the tertiary. The concave tertiary mirror is positioned exactly twice as far to the side of the entering beam as

768-468: A filter located between the second and third lenses, and an automatic filter-changing mechanism. Although the camera has six filters ( ugrizy ) covering 330–1080 nm wavelengths, the camera's position between the secondary and tertiary mirrors limits the size of its filter changer. It can hold five filters at a time, so each day one of the six must be chosen to be omitted for the following night. Allowing for maintenance, bad weather and other contingencies,

864-412: A given size of primary, and is popular with amateur telescope makers as a home-build project. The Cassegrain telescope (sometimes called the "Classic Cassegrain") was first published in a 1672 design attributed to Laurent Cassegrain . It has a parabolic primary mirror, and a hyperbolic secondary mirror that reflects the light back down through a hole in the primary. The folding and diverging effect of

960-456: A major initiative. Even at this early stage the basic design and objectives were set: The Large-aperture Synoptic Survey Telescope (LSST) is a 6.5-m-class optical telescope designed to survey the visible sky every week down to a much fainter level than that reached by existing surveys. It will catalog 90 percent of the near-Earth objects larger than 300 m and assess the threat they pose to life on Earth. It will find some 10,000 primitive objects in

1056-526: A much more compact instrument, one which can sometimes be successfully mounted on the Cassegrain focus. Since inexpensive and adequately stable computer-controlled alt-az telescope mounts were developed in the 1980s, the Nasmyth design has generally supplanted the coudé focus for large telescopes. For instruments requiring very high stability, or that are very large and cumbersome, it is desirable to mount

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1152-408: A narrower field of view than a Nasmyth focus and is used with very heavy instruments that do not need a wide field of view. One such application is high-resolution spectrographs that have large collimating mirrors (ideally with the same diameter as the telescope's primary mirror) and very long focal lengths. Such instruments could not withstand being moved, and adding mirrors to the light path to form

1248-630: A plethora of images, other data, and catalogs. In August 2001, the NSF allocated funding for a proposal entitled "Framework for the National Virtual Observatory ". The grant was approved under its Information Technology Research program (since superseded). NVO funding supported collaboration to produce a distributed computing framework for an integrated cyber infrastructure for astronomers providing seamless access to these astronomical resources. The manifestation of this infrastructure

1344-560: A shadow on the primary. However, while eliminating diffraction patterns this leads to an increase in coma and astigmatism. These defects become manageable at large focal ratios — most Schiefspieglers use f/15 or longer, which tends to restrict useful observations to objects which fit in a moderate field of view. A 6" (150mm) f/15 telescope offers a maximum 0.75 degree field of view using 1.25" eyepieces. A number of variations are common, with varying numbers of mirrors of different types. The Kutter (named after its inventor Anton Kutter ) style uses

1440-450: A single concave primary, a convex secondary and a plano-convex lens between the secondary mirror and the focal plane, when needed (this is the case of the catadioptric Schiefspiegler ). One variation of a multi-schiefspiegler uses a concave primary, convex secondary and a parabolic tertiary. One of the interesting aspects of some Schiefspieglers is that one of the mirrors can be involved in the light path twice — each light path reflects along

1536-500: A small diagonal mirror in an optical configuration that has come to be known as the Newtonian telescope . Despite the theoretical advantages of the reflector design, the difficulty of construction and the poor performance of the speculum metal mirrors being used at the time meant it took over 100 years for them to become popular. Many of the advances in reflecting telescopes included the perfection of parabolic mirror fabrication in

1632-400: A spectacle correcting lens is added between the secondary mirror and the focal plane ( catadioptric Yolo ). The addition of a convex, long focus tertiary mirror leads to Leonard's Solano configuration. The Solano telescope doesn't contain any toric surfaces. One design of telescope uses a rotating mirror consisting of a liquid metal in a tray that is spun at constant speed. As the tray spins,

1728-529: A very wide field of view: 3.5 degrees in diameter, or 9.6 square degrees. For comparison, both the Sun and the Moon, as seen from Earth, are 0.5 degrees across, or 0.2 square degrees. Combined with its large aperture (and thus light-collecting ability), this will give it a spectacularly large etendue of 319 m⋅degree. This is more than three times the etendue of the largest-view existing telescopes,

1824-610: A wide-field survey instrument with a sensitivity similar to LSST but one fifth the field of view: 1.8 square degrees versus the 9.6 square degrees of LSST. New software called HelioLinc3D was developed specifically for the Rubin Observatory, to detect moving objects. LSST will cover about 18,000 deg of the southern sky with six filters in its main survey, with about 825 visits to each spot. The 5σ ( SNR greater than 5) magnitude limits are expected to be r  < 24.5 in single images, and r  < 27.8 in

1920-645: A year, by re-processing the entire science data set to date. These include: The annual release will be computed partially by the National Center for Supercomputing Applications , and partially by IN2P3 in France. LSST is reserving 10% of its computing power and disk space for user generated data products. These will be produced by running custom algorithms over the LSST data set for specialized purposes, using application programming interfaces (APIs) to access

2016-503: Is 8.4 meters (28 ft) in diameter, the secondary mirror (M2) is 3.4 meters (11.2 ft) in diameter, and the tertiary mirror (M3), inside the ring-like primary, is 5.0 meters (16 ft) in diameter. The secondary mirror is expected to be the largest convex mirror in any operating telescope, until surpassed by the Extremely Large Telescope 's 4.2 m secondary in about 2028. The second and third mirrors reduce

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2112-402: 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 alternative to the refracting telescope which, at that time, was a design that suffered from severe chromatic aberration . Although reflecting telescopes produce other types of optical aberrations , it

2208-411: Is a design that allows for very large diameter objectives . Almost all of the major telescopes used in astronomy research are reflectors. Many variant forms are in use and some employ extra optical elements to improve image quality or place the image in a mechanically advantageous position. Since reflecting telescopes use mirrors , the design is sometimes referred to as a catoptric telescope . From

2304-481: Is a significant software engineering problem by itself. Approximately 10 million alerts will be generated per night. Each alert will include the following: There is no proprietary period associated with alerts—they are available to the public immediately, since the goal is to quickly transmit nearly everything LSST knows about any given event, enabling downstream classification and decision making. LSST will generate an unprecedented rate of alerts, hundreds per second when

2400-644: Is named the Simonyi Survey Telescope, after private donors Charles and Lisa Simonyi. The LSST is the successor to a tradition of sky surveys . These started as visually compiled catalogs in the 18th century, such as the Messier catalog . This was replaced by photographic surveys, starting with the 1885 Harvard Plate Collection , the National Geographic Society – Palomar Observatory Sky Survey , and others. By about 2000,

2496-413: Is reduced by deformation of the secondary mirror by some form of warping harness, or alternatively, polishing a toroidal figure into the secondary. Like Schiefspieglers, many Yolo variations have been pursued. The needed amount of toroidal shape can be transferred entirely or partially to the primary mirror. In large focal ratios optical assemblies, both primary and secondary mirror can be left spherical and

2592-578: Is replaced by a metal surface for reflecting radio waves , and the observer is an antenna . For telescopes built to the Cassegrain design or other related designs, the image is formed behind the primary mirror, at the focal point of the secondary mirror . An observer views through the rear of the telescope, or a camera or other instrument is mounted on the rear. Cassegrain focus is commonly used for amateur telescopes or smaller research telescopes. However, for large telescopes with correspondingly large instruments, an instrument at Cassegrain focus must move with

2688-410: Is the largest lens ever built, and the third lens forms the vacuum window in front of the focal plane. Unlike many telescopes, the Rubin Observatory makes no attempt to compensate for dispersion in the atmosphere. Such correction, which requires re-adjusting an additional element in the optical train, would be very difficult in the 5 seconds allowed between pointings, plus is a technical challenge due to

2784-679: The 2 Micron All Sky Survey (2MASS). Also found in the NVO are NASA 's rich data collections including data from the Hubble Space Telescope , the Chandra X-ray Observatory , the Spitzer Space Telescope , and other space -based missions. The NVO Closeout Repository provides access to a variety of additional data from nearly every astronomical research facility, observatory, and telescope across

2880-479: The Chandra Deep Field South . Combined, these special programs will increase the total area to about 25,000 deg. Particular scientific goals of the LSST include: Because of its wide field of view and sensitivity, LSST is expected to be among the best prospects for detecting optical counterparts to gravitational wave events detected by LIGO and other observatories. It is also hoped that

2976-545: The Hubble Space Telescope , and popular amateur models use this design. In addition, the reflection telescope principle was applied to other electromagnetic wavelengths, and for example, X-ray telescopes also use the reflection principle to make image-forming optics . The idea that curved mirrors behave like lenses dates back at least to Alhazen 's 11th century treatise on optics, works that had been widely disseminated in Latin translations in early modern Europe . Soon after

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3072-567: The Kuiper Belt , which contains a fossil record of the formation of the solar system. It will also contribute to the study of the structure of the universe by observing thousands of supernovae , both nearby and at large redshift, and by measuring the distribution of dark matter through gravitational lensing. All the data will be available through the National Virtual Observatory ... providing access for astronomers and

3168-493: The Ritchey–Chrétien telescope ) or some form of correcting lens (such as catadioptric telescopes ) that correct some of these aberrations. Nearly all large research-grade astronomical telescopes are reflectors. There are several reasons for this: The Gregorian telescope , described by Scottish astronomer and mathematician James Gregory in his 1663 book Optica Promota , employs a concave secondary mirror that reflects

3264-509: The Subaru Telescope with its Hyper Suprime Camera and Pan-STARRS , and more than an order of magnitude better than most large telescopes. The earliest reflecting telescopes used spherical mirrors which, although easy to fabricate and test, suffer from spherical aberration ; a long focal length was needed to reduce spherical aberration to a tolerable level. Making the primary mirror parabolic removes spherical aberration on-axis, but

3360-607: The University of Wisconsin–Madison , and National Radio Astronomy Observatory . The NVO, a US effort, had affiliates throughout the international astronomical community including IVOA , AstroGrid (UK), Euro-VO , the Japanese VO, the Australian VO, VO India and ten other national programs. Along with its objective to serve the scientific community by enabling research through distributed data sources and services,

3456-557: The Vera C. Rubin Observatory was initiated by United States Representative Eddie Bernice Johnson and Jenniffer González-Colón . The renaming was enacted into United States law on December 20, 2019, and announced at the 2020 American Astronomical Society winter meeting. The observatory is named after Vera C. Rubin . The name honors Rubin and her colleagues' legacy to probe the nature of dark matter by mapping and cataloging billions of galaxies through space and time. The telescope itself

3552-465: The 18th century, silver coated glass mirrors in the 19th century (built by Léon Foucault in 1858), long-lasting aluminum coatings in the 20th century, segmented mirrors to allow larger diameters, and active optics to compensate for gravitational deformation. A mid-20th century innovation was catadioptric telescopes such as the Schmidt camera , which use both a spherical mirror and a lens (called

3648-522: The 30 terabytes of data LSST will produce each night. As of February 2018, construction was well underway. The shell of the summit building was complete, and 2018 saw the installation of major equipment, including HVAC , the dome, mirror coating chamber, and the telescope mount assembly. It also saw the expansion of the AURA base facility in La Serena and the summit dormitory shared with other telescopes on

3744-564: The CCDs. The camera focal plane is flat and 64 cm in diameter. The main imaging is performed by a mosaic of 189 CCD detectors, each with 16 megapixels . They are grouped into a 5×5 grid of "rafts", where the central 21 rafts contain 3×3 imaging sensors, while the four corner rafts contain only three CCDs each, for guiding and focus control. The CCDs provide better than 0.2 arcsecond sampling, and will be cooled to approximately −100 °C (173 K) to help reduce noise. The camera includes

3840-782: The FY2014 portion ($ 27.5 million) of its construction budget. Funding comes from the NSF, the United States Department of Energy , and private funding raised by the dedicated international non-profit organization, the LSST Discovery Alliance. Operations are under the management of the Association of Universities for Research in Astronomy (AURA). Total construction cost is expected to be about $ 680 million. Site construction began on 14 April 2015 with

3936-510: The Hale use this design—the Hubble and Keck telescopes are Ritchey–Chrétien, for example. LSST will use a three-mirror anastigmat to cancel astigmatism by employing three non-spherical mirrors. The result is sharp images over a wide field of view, but at the expense of some light-gathering power due to the large tertiary mirror obscuring part of the optical path. The telescope's primary mirror (M1)

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4032-575: The NVO began with combined funding from NSF and NASA and programmatically executed through NSF. Scientists originally accessed the NVO through the NVO website. Data in the NVO Closeout Repository are available from a variety of observatories and wavelengths , including NSF 's National Optical Astronomy Observatory (NOAO), National Radio Astronomy Observatory (NRAO), the Sloan Digital Sky Survey (SDSS), and

4128-547: The Petzval surface which is gently curved. The Yolo was developed by Arthur S. Leonard in the mid-1960s. Like the Schiefspiegler, it is an unobstructed, tilted reflector telescope. The original Yolo consists of a primary and secondary concave mirror, with the same curvature, and the same tilt to the main axis. Most Yolos use toroidal reflectors . The Yolo design eliminates coma, but leaves significant astigmatism, which

4224-421: The camera is expected to take over 200,000 pictures (1.28  petabytes uncompressed) per year, far more than can be reviewed by humans. Managing and effectively analyzing the enormous output of the telescope is expected to be the most technically difficult part of the project. In 2010, the initial computer requirements were estimated at 100 teraflops of computing power and 15 petabytes of storage, rising as

4320-438: The camera. The 15-second exposures are a compromise to allow spotting both faint and moving sources. Longer exposures would reduce the overhead of camera readout and telescope re-positioning, allowing deeper imaging, but then fast moving objects such as near-Earth objects would move significantly during an exposure. Each spot on the sky is imaged with two consecutive 15 second exposures, to efficiently reject cosmic ray hits on

4416-518: The center of the mirror, a defect called spherical aberration . To avoid this problem most reflecting telescopes use parabolic shaped mirrors , a shape that can focus all the light to a common focus. Parabolic mirrors work well with objects near the center of the image they produce, (light traveling parallel to the mirror's optical axis ), but towards the edge of that same field of view they suffer from off axis aberrations: There are reflecting telescope designs that use modified mirror surfaces (such as

4512-623: The ceremonial laying of the first stone. First light for the engineering camera is expected in August 2024, while system first light is expected in January 2025 and full survey operations are aimed to begin in August 2025, due to COVID -related schedule delays. LSST data is scheduled to become fully public after two years. In June 2019, the renaming of the observatory from the Large Synoptic Survey Telescope (LSST) to

4608-463: The commissioning camera arrived at the base facility and was tested there. It was moved to the summit and installed on the mount in August 2022. The primary mirror, the most critical and time-consuming part of a large telescope's construction, was made over a 7-year period by the University of Arizona 's Steward Observatory Mirror Lab. Construction of the mold began in November 2007, mirror casting

4704-411: The components are centered and are close to the intended positions. (2) Open loop corrections are applied to correct for intrinsic mirror aberrations, component sag as a function of elevation and temperature, and filter selection. (3) Focus and figure measurements are made during normal operation by sensors at the corners of the field of view, and used to correct the optics. The precise shape and focus of

4800-409: The corrections from the out of focus images. Both methods appear capable of meeting the design goals. A 3.2-gigapixel prime focus digital camera will take a 15-second exposure every 20 seconds. Repointing such a large telescope (including settling time) within 5 seconds requires an exceptionally short and stiff structure. This in turn implies a small f-number , which requires precise focusing of

4896-401: The data and store the results. This avoids the need to download, then upload, huge quantities of data by allowing users to use the LSST storage and computation capacity directly. It also allows academic groups to have different release policies than LSST as a whole. An early version of the LSST image data processing software is being used by the Subaru Telescope 's Hyper Suprime-Cam instrument,

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4992-587: The digital camera component by the SLAC National Accelerator Laboratory , as part of its mission to understand dark energy. In the 2010 decadal survey , LSST was ranked as the highest-priority ground-based instrument. NSF funding for the rest of construction was authorized as of 1 August 2014. The lead organizations are: In May 2018, the United States Congress surprisingly appropriated much more funding than

5088-402: The exact figure needed. Reflecting telescopes, just like any other optical system, do not produce "perfect" images. The need to image objects at distances up to infinity, view them at different wavelengths of light, along with the requirement to have some way to view the image the primary mirror produces, means there is always some compromise in a reflecting telescope's optical design. Because

5184-496: The experimental scientist Robert Hooke was able to build this type of telescope, which became known as the Gregorian telescope . Five years after Gregory designed his telescope and five years before Hooke built the first such Gregorian telescope, Isaac Newton in 1668 built his own reflecting telescope , which is generally acknowledged as the first reflecting telescope. It used a spherically ground metal primary mirror and

5280-476: The extremely short focal length. As a result, shorter wavelength bands away from the zenith will have somewhat reduced image quality. The Simonyi telescope uses an active optics system, with wavefront sensors at the corners of the camera, to keep the mirrors accurately figured and in focus. The field of view is too large to use adaptive optics to correct for atmospheric seeing. The process occurs in three stages: (1) Laser tracker measurements are used to make sure

5376-526: The field of view is then limited by off-axis coma . Such a parabolic primary, with either a prime or Cassegrain focus, was the most common optical design up through the Hale Telescope in 1949. After that, telescopes used mostly the Ritchey–Chrétien design, using two hyperbolic mirrors to remove both spherical aberration and coma, giving a wider useful field of view limited only by astigmatism and higher order aberrations. Most large telescopes since

5472-542: The first digital surveys, such as the Sloan Digital Sky Survey (SDSS), began to replace the photographic plates of the earlier surveys. LSST evolved from the earlier concept of the Dark Matter Telescope , mentioned as early as 1996. The fifth decadal report , Astronomy and Astrophysics in the New Millennium , was released in 2001, and recommended the "Large-Aperture Synoptic Survey Telescope" as

5568-454: The focal plane. The distance from the mirror to the focal plane is called the focal length . Film or a digital sensor may be located here to record the image, or a secondary mirror may be added to modify the optical characteristics and/or redirect the light to film, digital sensors, or an eyepiece for visual observation. The primary mirror in most modern telescopes is composed of a solid glass cylinder whose front surface has been ground to

5664-519: The full stacked data. The main survey will use about 90% of the observing time. The remaining 10% will be used to obtain improved coverage for specific goals and regions. This includes very deep ( r ~ 26) observations, very short revisit times (roughly one minute), observations of "special" regions such as the ecliptic , galactic plane , and the Large and Small Magellanic Clouds , and areas covered in detail by multi-wavelength surveys such as COSMOS and

5760-808: The globe. The NVO development project was distributed across many institutions and includes teams at the Johns Hopkins University , California Institute of Technology , Space Telescope Science Institute , NOAO , Infrared Processing and Analysis Center , San Diego Supercomputer Center , and the Associated Universities, Inc . Affiliate organizations with participating teams include Goddard Space Flight Center , Carnegie Mellon University , University of Pittsburgh , National Center for Supercomputing Applications , Smithsonian Astrophysical Observatory , University of Southern California , Fermilab , United States Naval Observatory ,

5856-733: The image back through a hole in the primary mirror. This produces an upright image, useful for terrestrial observations. Some small spotting scopes are still built this way. There are several large modern telescopes that use a Gregorian configuration such as the Vatican Advanced Technology Telescope , the Magellan telescopes , the Large Binocular Telescope , and the Giant Magellan Telescope . The Newtonian telescope

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5952-543: The images from that night, and the source catalogs derived from difference images. This includes orbital parameters for Solar System objects. Images will be available in two forms: Raw Snaps , or data straight from the camera, and Single Visit Images , which have been processed and include instrumental signature removal (ISR), background estimation, source detection, deblending and measurements, point spread function estimation, and astrometric and photometric calibration. Annual release data products will be made available once

6048-480: The incoming light by eliminating the secondary or moving any secondary element off the primary mirror's optical axis , commonly called off-axis optical systems . The Herschelian reflector is named after William Herschel , who used this design to build very large telescopes including the 40-foot telescope in 1789. In the Herschelian reflector the primary mirror is tilted so the observer's head does not block

6144-410: The incoming light. Although this introduces geometrical aberrations, Herschel employed this design to avoid the use of a Newtonian secondary mirror since the speculum metal mirrors of that time tarnished quickly and could only achieve 60% reflectivity. A variant of the Cassegrain, the Schiefspiegler telescope ("skewed" or "oblique reflector") uses tilted mirrors to avoid the secondary mirror casting

6240-423: The instrument on a rigid structure, rather than moving it with the telescope. Whilst transmission of the full field of view would require a standard coudé focus, spectroscopy typically involves the measurement of only a few discrete objects, such as stars or galaxies. It is therefore feasible to collect light from these objects with optical fibers at the telescope, placing the instrument at an arbitrary distance from

6336-575: The invention of the refracting telescope , Galileo , Giovanni Francesco Sagredo , and others, spurred on by their knowledge of the principles of curved mirrors, discussed the idea of building a telescope using a mirror as the image forming objective. There were reports that the Bolognese Cesare Caravaggi had constructed one around 1626 and the Italian professor Niccolò Zucchi , in a later work, wrote that he had experimented with

6432-466: The light to the side of the telescope to allow for the mounting of heavy instruments. This is a very common design in large research telescopes. Adding further optics to a Nasmyth-style telescope to deliver the light (usually through the declination axis) to a fixed focus point that does not move as the telescope is reoriented gives a coudé focus (from the French word for elbow). The coudé focus gives

6528-408: The liquid forms a paraboloidal surface of essentially unlimited size. This allows making very big telescope mirrors (over 6 metres), but they are limited to use by zenith telescopes . In a prime focus design no secondary optics are used, the image is accessed at the focal point of the primary mirror . At the focal point is some type of structure for holding a film plate or electronic detector. In

6624-465: The magazine editor at the time. It uses a concave elliptical primary mirror and a convex spherical secondary. While this system is easier to grind than a classic Cassegrain or Ritchey–Chrétien system, it does not correct for off-axis coma. Field curvature is actually less than a classical Cassegrain. Because this is less noticeable at longer focal ratios , Dall–Kirkhams are seldom faster than f/15. There are several designs that try to avoid obstructing

6720-421: The main currently used optical surveys, with differences noted: The Cerro Pachón site was selected in 2006. The main factors were the number of clear nights per year, seasonal weather patterns, and the quality of images as seen through the local atmosphere (seeing). The site also needed to have an existing observatory infrastructure, to minimize costs of construction, and access to fiber optic links, to accommodate

6816-497: The mirror assembly is estimated, and then corrected, by comparing the images on four sets of deliberately defocused CCDs (one in front of the focal plane and one behind, see figure at right). Two methods for finding these corrections have been developed. One proceeds analytically, estimating a Zernike polynomial description of the current shape of the mirror, and from this computing a set of corrections to restore figure and focus. The other method uses machine learning to directly compute

6912-529: The mirror support cell. It went through additional testing in January/February 2019, then was returned to its shipping crate. In March 2019, it was sent by truck to Houston, Texas, was placed on a ship for delivery to Chile, and arrived on the summit in May. There it will be re-united with the mirror support cell and coated. Reflecting telescope A reflecting telescope (also called a reflector )

7008-600: The most cost-effective way of finishing the task. Rubin Observatory has a program of Education and Public Outreach (EPO). Rubin Observatory EPO will serve four main categories of users: the general public, formal educators, citizen science principal investigators, and content developers at informal science education facilities. Rubin Observatory will partner with Zooniverse for a number of their citizen science projects. There have been many other optical sky surveys , some still on-going. For comparison, here are some of

7104-498: The mountain. By February 2018, the camera and telescope shared the critical path. The main risk was deemed to be whether sufficient time was allotted for system integration. As of 2017, the project remained within budget, although the budget contingency was tight. In March 2020, work on the summit facility, and the main camera at SLAC, was suspended due to the COVID-19 pandemic, though work on software continued. During this time,

7200-400: The obstruction as well as diffraction spikes caused by most secondary support structures. The use of mirrors avoids chromatic aberration but they produce other types of aberrations . A simple spherical mirror cannot bring light from a distant object to a common focus since the reflection of light rays striking the mirror near its edge do not converge with those that reflect from nearer

7296-426: The past, in very large telescopes, an observer would sit inside the telescope in an "observing cage" to directly view the image or operate a camera. Nowadays CCD cameras allow for remote operation of the telescope from almost anywhere in the world. The space available at prime focus is severely limited by the need to avoid obstructing the incoming light. Radio telescopes often have a prime focus design. The mirror

7392-432: The primary mirror focuses light to a common point in front of its own reflecting surface almost all reflecting telescope designs have a secondary mirror , film holder, or detector near that focal point partially obstructing the light from reaching the primary mirror. Not only does this cause some reduction in the amount of light the system collects, it also causes a loss in contrast in the image due to diffraction effects of

7488-413: The primary mirror's light-collecting area to 35 square meters (376.7 sq ft), equivalent to a 6.68-meter-diameter (21.9 ft) telescope. Multiplying this by the field of view produces an étendue of 336 m⋅degree; the actual figure is reduced by vignetting . The primary and tertiary mirrors (M1 and M3) are designed as a single piece of glass, the "M1M3 monolith". Placing the two mirrors in

7584-552: The project collects data. By 2018, estimates had risen to 250 teraflops and 100 petabytes of storage. Once images are taken, they are processed according to three different timescales, prompt (within 60 seconds), daily , and annually . The prompt products are alerts, issued within 60 seconds of observation, about objects that have changed brightness or position relative to archived images of that sky position. Transferring, processing, and differencing such large images within 60 seconds (previous methods took hours, on smaller images)

7680-418: The public to very deep images of the changing night sky. Early development was funded by a number of small grants, with major contributions in January 2008 by software billionaires Charles and Lisa Simonyi and Bill Gates of $ 20 million and $ 10 million, respectively. $ 7.5 million was included in the U.S. President's FY2013 NSF budget request. The United States Department of Energy is funding construction of

7776-436: The same location minimizes the overall length of the telescope, making it easier to reorient quickly. Making them out of the same piece of glass results in a stiffer structure than two separate mirrors, contributing to rapid settling after motion. The optics includes three corrector lenses to reduce aberrations. These lenses, and the telescope's filters, are built into the camera assembly. The first lens, at 1.55 m diameter,

7872-574: The secondary mirror creates a telescope with a long focal length while having a short tube length. The Ritchey–Chrétien telescope, invented by George Willis Ritchey and Henri Chrétien in the early 1910s, is a specialized Cassegrain reflector which has two hyperbolic mirrors (instead of a parabolic primary). It is free of coma and spherical aberration at a nearly flat focal plane if the primary and secondary curvature are properly figured , making it well suited for wide field and photographic observations. Almost every professional reflector telescope in

7968-418: The telescope as it slews; this places additional requirements on the strength of the instrument support structure, and potentially limits the movement of the telescope in order to avoid collision with obstacles such as walls or equipment inside the observatory. The Nasmyth design is similar to the Cassegrain except the light is not directed through a hole in the primary mirror; instead, a third mirror reflects

8064-416: The telescope had asked for, in hopes of speeding construction and operation. Telescope management was thankful but unsure this would help, since at the late stage of construction they were not cash-limited. As of May 2022, the project critical path was the camera installation, integration and testing. The Simonyi Survey Telescope design is unique among large telescopes (8 m-class primary mirrors) in having

8160-471: The telescope is operating. Most observers will be interested in only a tiny fraction of these events, so the alerts will be fed to "event brokers" which forward subsets to interested parties. LSST will provide a simple broker, and provide the full alert stream to external event brokers. The Zwicky Transient Facility will serve as a prototype of LSST system, generating 1 million alerts per night. Daily products, released within 24 hours of observation, comprise

8256-772: The telescope. Examples of fiber-fed spectrographs include the planet-hunting spectrographs HARPS or ESPRESSO . Additionally, the flexibility of optical fibers allow light to be collected from any focal plane; for example, the HARPS spectrograph utilises the Cassegrain focus of the ESO 3.6 m Telescope , whilst the Prime Focus Spectrograph is connected to the prime focus of the Subaru telescope . National Virtual Observatory The US National Virtual Observatory' -NVO- (nowadays VAO - Virtual Astronomical Observatory)

8352-459: The time of Newton to the 1800s, the mirror itself was made of metal – usually speculum metal . This type included Newton's first designs and the largest telescope of the 19th century, the Leviathan of Parsonstown with a 6 feet (1.8 m) wide metal mirror. In the 19th century a new method using a block of glass coated with very thin layer of silver began to become more popular by

8448-595: The turn of the century. Common telescopes which led to the Crossley and Harvard reflecting telescopes, which helped establish a better reputation for reflecting telescopes as the metal mirror designs were noted for their drawbacks. Chiefly the metal mirrors only reflected about 2 ⁄ 3 of the light and the metal would tarnish . After multiple polishings and tarnishings, the mirror could lose its precise figuring needed. Reflecting telescopes became extraordinarily popular for astronomy and many famous telescopes, such as

8544-514: The vast volume of data produced will lead to additional serendipitous discoveries. NASA has been tasked by the U.S. Congress with detecting and cataloging 90% of the near Earth orbit population of size 140 meters or greater. LSST, by itself, is estimated to be capable of detecting 62% of such objects, and according to the United States National Academy of Sciences , extending its survey from ten years to twelve would be

8640-591: The world is of the Ritchey–Chrétien design. Including a third curved mirror allows correction of the remaining distortion, astigmatism, from the Ritchey–Chrétien design. This allows much larger fields of view. The Dall–Kirkham Cassegrain telescope's design was created by Horace Dall in 1928 and took on the name in an article published in Scientific American in 1930 following discussion between amateur astronomer Allan Kirkham and Albert G. Ingalls,

8736-694: Was a vibrant, growing online research facility akin to a bricks-and-mortar observatory for professional astronomers. As of October 1, 2014, funding ceased for the National Virtual Observatory (NVO) and all code and digital assets of the project were made publicly available at the VAO Closeout Repository. The NVO was conceived to allow scientists to grapple with the enormous growth in astronomical data resulting from significant advances in telescope , detector , and computer technologies. These advances have resulted in

8832-400: Was an operational “virtual observatory” available to scientists and to the public. Investigators acquired existing astronomical data from a variety of observatory archives through “virtual instruments”, that is, computer interfaces, tools, and services. The NVO was planned and implemented in synergy with the research community, the primary users of the system. In 2007, the operational stage of

8928-474: Was begun in March 2008, and the mirror blank was declared "perfect" at the beginning of September 2008. In January 2011, both M1 and M3 figures had completed generation and fine grinding, and polishing had begun on M3. The mirror was formally accepted on 13 February 2015, then placed in the mirror transport box and stored in an airplane hangar. In October 2018, it was moved back to the mirror lab and integrated with

9024-480: Was conceived to allow scientists to access data from multiple astronomical observatories , including ground and space-based facilities, through a single portal. Originally, the National Science Foundation (NSF) funded the information technology research that created the basic NVO infrastructure through a multi-organization collaborative effort. The NVO was more than a “digital library”; it

9120-419: Was the convex secondary, and its own radius of curvature distant from the secondary. Because the tertiary mirror receives parallel light from the secondary, it forms an image at its focus. The focal plane lies within the system of mirrors, but is accessible to the eye with the inclusion of a flat diagonal. The Stevick-Paul configuration results in all optical aberrations totaling zero to the third-order, except for

9216-409: Was the first successful reflecting telescope, completed by Isaac Newton in 1668. It usually has a paraboloid primary mirror but at focal ratios of about f/10 or longer a spherical primary mirror can be sufficient for high visual resolution. A flat secondary mirror reflects the light to a focal plane at the side of the top of the telescope tube. It is one of the simplest and least expensive designs for

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