1.
Mount Graham International Observatory
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Mount Graham International Observatory is a division of Steward Observatory, the research arm for the Department of Astronomy at The University of Arizona, in the United States. It is located in southeastern Arizonas Pinaleño Mountains near Mount Graham, scientific researchers from around the world make use of the MGIO facilities. Construction of MGIO began in 1989, MGIO currently operates and maintains facilities for three scientific organizations. The first two telescopes, the Vatican Advanced Technology Telescope and the Heinrich Hertz Submillimeter Telescope began operations in 1993, public tours of the MGIO are conducted by the Eastern Arizona Colleges Discovery Park Campus. Weather permitting, tours are allowed between mid-April and mid-October, reservations and permits must be obtained at least one week in advance through EACs Discovery Park Campus. For information about the tours, call +1-928-428-6260, or search for the Discovery Park Campus contact info on the Eastern Arizona College webpage, Large Binocular Telescope operated by the Large Binocular Telescope Corporation. Heinrich Hertz Submillimeter Telescope, operated by Arizona Radio Observatory, Vatican Advanced Technology Telescope, operated by the Vatican Observatory. List of observatories Official website Mount Graham Clear Sky Clock Satellite Picture - Yahoo Maps Driving Directions Map
2.
Steward Observatory
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Steward Observatory is the research arm of the Department of Astronomy at the University of Arizona. Its offices are located on the UA campus in Tucson, Arizona, established in 1916, the first telescope and building were formally dedicated on April 23,1923. It now operates, or is a partner in telescopes at five locations in Arizona, one in New Mexico, one in Hawaii. It has provided instruments for three different space telescopes and numerous terrestrial ones, Steward also has one of the few facilities in the world that can cast and figure the very large primary mirrors used in telescopes built in the past decade. Steward Observatory owes its existence to the efforts of American astronomer, in 1906, Douglass accepted a position as Assistant Professor of Physics and Geography at the University of Arizona in Tucson, Arizona. Over the next 10 years, all of Douglass’ efforts to secure funding from the University and the Arizona Territorial Legislatures ended in failure. During this time period, Douglass served the University of Arizona as Head of the Dept. of Physics and Astronomy, Interim President, and finally Dean of the College of Letters, Arts, & Sciences. Then on October 18,1916, University President Rufus von KleinSmid announced that a donor had given the University $60,000 “…to be used to buy a telescope of huge size. ”That donor was later revealed to be Mrs. Lavinia Steward of Oracle. Mrs. Steward was a widow who had an interest in astronomy. Douglass made plans to use the Steward gift to construct a 36-inch diameter Newtonian reflecting telescope, the situation was further delayed by the fact that up until this time, the expertise in large telescope mirror making was in Europe. The war made it impossible to contract with a European company, so Douglass had to find an American glass company that was willing to develop this expertise. After a couple of failed castings, the Spencer Lens Co. of Buffalo, the telescope was finally installed in the observatory building in July 1922, and the Steward Observatory was officially dedicated on April 23,1923. This installation is to be devoted to scientific research, scientific research is business foresight on a large scale. It is knowledge obtained before it is needed and this I believe is the essence of education wherever such education is not strictly vocational. The student learns many facts and has much training, so it is with the research institutions. In this Observatory I sincerely hope and expect that the boundaries of knowledge will be advanced along astronomical lines. Astronomy was the first science developed by our primitive ancestors thousands of years ago because it measured time, Steward Observatory manages three different observing locations in southern Arizona, Mount Graham International Observatory, Mount Lemmon Observatory, and Catalina Station on Mount Bigelow. It also operates telescopes at two additional important observatories, Kitt Peak National Observatory and Fred Lawrence Whipple Observatory on Mount Hopkins, Steward is a partner in the Sloan Digital Sky Survey-III, which is located in New Mexico at Apache Point Observatory
3.
Mount Graham
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Mount Graham is a mountain in southeastern Arizona in the United States. The mountain reaches 10,720 feet in height and it is twentieth of the 57 ultra prominent peaks of the lower 48 states, and the first of the five in Arizona. Mount Graham summits are headwaters for numerous streams that tumble through five major botanical zones. Of particular note are stands of the oldest conifer trees in the U. S, southwest and associated habitats for threatened and endangered species, especially the Mount Graham Red Squirrel. In 1993, the St. Paisius Orthodox Monastery was founded at the base of the mountain, Mount Graham hosts both species of Arizona native trout--Gila and Apache trout and three species of introduced trout. S. Environmental groups, including the Sierra Club also oppose the Mount Graham International Observatory because the higher elevations are the last remaining habitat for the Mount Graham Red Squirrel, list of Ultras of the United States Heinrich Hertz Submillimeter Telescope Large Binocular Telescope Vatican Advanced Technology Telescope Mount Graham. Mount Graham International Observatory home page
4.
Arizona
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Arizona is a state in the southwestern region of the United States. It is also part of the Western United States and the Mountain West states and it is the sixth largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix, Arizona is one of the Four Corners states. It has borders with New Mexico, Utah, Nevada, California, and Mexico, Arizonas border with Mexico is 389 miles long, on the northern border of the Mexican states of Sonora and Baja California. Arizona is the 48th state and last of the states to be admitted to the Union. Historically part of the territory of Alta California in New Spain, after being defeated in the Mexican–American War, Mexico ceded much of this territory to the United States in 1848. The southernmost portion of the state was acquired in 1853 through the Gadsden Purchase, Southern Arizona is known for its desert climate, with very hot summers and mild winters. There are ski resorts in the areas of Flagstaff, Alpine, in addition to the Grand Canyon National Park, there are several national forests, national parks, and national monuments. To the European settlers, their pronunciation sounded like Arissona, the area is still known as alĭ ṣonak in the Oodham language. Another possible origin is the Basque phrase haritz ona, as there were numerous Basque sheepherders in the area, There is a misconception that the states name originated from the Spanish term Árida Zona. See also lists of counties, islands, rivers, lakes, state parks, national parks, Arizona is in the Southwestern United States as one of the Four Corners states. Arizona is the sixth largest state by area, ranked after New Mexico, of the states 113,998 square miles, approximately 15% is privately owned. The remaining area is public forest and park land, state trust land, Arizona is well known for its desert Basin and Range region in the states southern portions, which is rich in a landscape of xerophyte plants such as the cactus. This regions topography was shaped by volcanism, followed by the cooling-off. Its climate has hot summers and mild winters. The state is well known for its pine-covered north-central portion of the high country of the Colorado Plateau. Like other states of the Southwest United States, Arizona has an abundance of mountains, despite the states aridity, 27% of Arizona is forest, a percentage comparable to modern-day France or Germany. The worlds largest stand of pine trees is in Arizona
5.
Geographic coordinate system
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A geographic coordinate system is a coordinate system used in geography that enables every location on Earth to be specified by a set of numbers, letters or symbols. The coordinates are chosen such that one of the numbers represents a vertical position. A common choice of coordinates is latitude, longitude and elevation, to specify a location on a two-dimensional map requires a map projection. The invention of a coordinate system is generally credited to Eratosthenes of Cyrene. Ptolemy credited him with the adoption of longitude and latitude. Ptolemys 2nd-century Geography used the prime meridian but measured latitude from the equator instead. Mathematical cartography resumed in Europe following Maximus Planudes recovery of Ptolemys text a little before 1300, in 1884, the United States hosted the International Meridian Conference, attended by representatives from twenty-five nations. Twenty-two of them agreed to adopt the longitude of the Royal Observatory in Greenwich, the Dominican Republic voted against the motion, while France and Brazil abstained. France adopted Greenwich Mean Time in place of local determinations by the Paris Observatory in 1911, the latitude of a point on Earths surface is the angle between the equatorial plane and the straight line that passes through that point and through the center of the Earth. Lines joining points of the same latitude trace circles on the surface of Earth called parallels, as they are parallel to the equator, the north pole is 90° N, the south pole is 90° S. The 0° parallel of latitude is designated the equator, the plane of all geographic coordinate systems. The equator divides the globe into Northern and Southern Hemispheres, the longitude of a point on Earths surface is the angle east or west of a reference meridian to another meridian that passes through that point. All meridians are halves of great ellipses, which converge at the north and south poles, the prime meridian determines the proper Eastern and Western Hemispheres, although maps often divide these hemispheres further west in order to keep the Old World on a single side. The antipodal meridian of Greenwich is both 180°W and 180°E, the combination of these two components specifies the position of any location on the surface of Earth, without consideration of altitude or depth. The grid formed by lines of latitude and longitude is known as a graticule, the origin/zero point of this system is located in the Gulf of Guinea about 625 km south of Tema, Ghana. To completely specify a location of a feature on, in, or above Earth. Earth is not a sphere, but a shape approximating a biaxial ellipsoid. It is nearly spherical, but has an equatorial bulge making the radius at the equator about 0. 3% larger than the radius measured through the poles, the shorter axis approximately coincides with the axis of rotation
6.
First light (astronomy)
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In astronomy, first light is the first use of a telescope to take an astronomical image after it has been constructed. This is often not the first viewing using the telescope, optical tests will probably have been performed during daylight to adjust the components. The first light image is normally of little scientific interest and is of poor quality since the various elements are yet to be adjusted for optimum efficiency. A well-known and spectacular astronomical object is chosen as a subject. For example, the 5. 08-metre Hale Telescope saw first light January 26,1949, the image was published in many magazines and is available on Caltech Archives. The Isaac Newton Telescope had two first lights, one in England in 1965 with its mirror, and another in 1984 at La Palma island. The second first light was done with a camera that showed the Crab Pulsar flashing. The Large Binocular Telescope had its first light with a primary mirror on October 12,2005. The second primary mirror was installed in January 2006 and became operational in January 2008. The 10.4 m Gran Telescopio Canarias had a first light image of Tycho 1205081 on 14 July 2007, the IRIS solar space observatory achieved first light on July 17,2013. The PI noted, The quality of images and spectra we are receiving from IRIS is amazing and this is just what we were hoping for
7.
Optical telescope
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The larger the objective, the more light the telescope collects and the finer detail it resolves. People use telescopes and binoculars for activities such as astronomy, ornithology, pilotage and reconnaissance. The telescope is more a discovery of optical craftsmen than an invention of a scientist and it is in the Netherlands in 1608 where the first recorded optical telescopes appeared. The invention is credited to the spectacle makers Hans Lippershey and Zacharias Janssen in Middelburg, galileo greatly improved on these designs the following year, and is generally credited as the first to use a telescope for astronomy. Galileos telescope used Hans Lippersheys design of an objective lens and a concave eye lens. Johannes Kepler proposed an improvement on the design used a convex eyepiece. For reflecting telescopes, which use a mirror in place of the objective lens. The theoretical basis for curved mirrors behaving similar to lenses was probably established by Alhazen, the late 20th century has seen the development of adaptive optics and space telescopes to overcome the problems of astronomical seeing. The basic scheme is that the primary light-gathering element the objective and this image may be recorded or viewed through an eyepiece, which acts like a magnifying glass. The eye then sees an inverted magnified virtual image of the object, most telescope designs produce an inverted image at the focal plane, these are referred to as inverting telescopes. In fact, the image is both turned upside down and reversed left to right, so that altogether it is rotated by 180 degrees from the object orientation, in astronomical telescopes the rotated view is normally not corrected, since it does not affect how the telescope is used. However, a diagonal is often used to place the eyepiece in a more convenient viewing location, and in that case the image is erect. In terrestrial telescopes such as spotting scopes, monoculars and binoculars, There are telescope designs that do not present an inverted image such as the Galilean refractor and the Gregorian reflector. These are referred to as erecting telescopes, many types of telescope fold or divert the optical path with secondary or tertiary mirrors. These may be part of the optical design, or may simply be used to place the eyepiece or detector at a more convenient position. Telescope designs may also use specially designed additional lenses or mirrors to improve image quality over a field of view. Design specifications relate to the characteristics of the telescope and how it performs optically, several properties of the specifications may change with the equipment or accessories used with the telescope, such as Barlow lenses, star diagonals and eyepieces. These interchangeable accessories dont alter the specifications of the telescope, however they alter the way the telescopes properties function, typically magnification, angular resolution and FOV
8.
Focal length
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The focal length of an optical system is a measure of how strongly the system converges or diverges light. For an optical system in air, it is the distance over which initially collimated rays are brought to a focus. A system with a focal length has greater optical power than one with a long focal length. For a thin lens in air, the length is the distance from the center of the lens to the principal foci of the lens. For a converging lens, the length is positive, and is the distance at which a beam of collimated light will be focused to a single spot. For a diverging lens, the length is negative, and is the distance to the point from which a collimated beam appears to be diverging after passing through the lens. The focal length of a lens can be easily measured by using it to form an image of a distant light source on a screen. The lens is moved until an image is formed on the screen. In this case 1/u is negligible, and the length is then given by f ≈ v. Back focal length or back focal distance is the distance from the vertex of the last optical surface of the system to the focal point. For an optical system in air, the focal length gives the distance from the front. If the surrounding medium is not air, then the distance is multiplied by the index of the medium. Some authors call these distances the front/rear focal lengths, distinguishing them from the front/rear focal distances, defined above. In general, the length or EFL is the value that describes the ability of the optical system to focus light. The other parameters are used in determining where an image will be formed for an object position. The quantity 1/f is also known as the power of the lens. The corresponding front focal distance is, FFD = f, in the sign convention used here, the value of R1 will be positive if the first lens surface is convex, and negative if it is concave. The value of R2 is negative if the surface is convex
9.
Telescope mount
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A telescope mount is a mechanical structure which supports a telescope. Telescope mounts are designed to support the mass of the telescope, many sorts of mounts have been developed over the years, with the majority of effort being put into systems that can track the motion of the stars as the Earth rotates. Fixed-altitude mounts usually have the primary optics fixed at an angle while rotating horizontally. They can cover the sky but only observe objects for the short time when that object passes a specific altitude. Transit mounts are single axis mounts fixed in azimuth while rotating in altitude and this allows the telescope to view the whole sky, but only when the Earths rotation allows the objects to cross through that narrow north-south line. This type of mount is used in Transit telescopes, designed for precision astronomical measurement, Transit mounts are also used to save on cost or where the instruments mass makes movement on more than one axis very difficult, such as large radio telescopes. Altazimuth, altitude-azimuth, or alt-az mounts allow telescopes to be moved in altitude, or azimuth and this meant until recently it was normally used with inexpensive commercial and hobby constructions. Since the invention of digital tracking systems, altazimuth mounts have come to be used in all modern large research telescopes. Digital tracking has also made it a popular telescope mount used in amateur astronomy, besides the mechanical inability to easily follow celestial motion the altazimuth mount does have other limitations. The mount also has blind spot or zenith hole, a spot near the zenith where the rate in the azimuth coordinate becomes too high to accurately follow equatorial motion. These mounts also require a third axis to de-rotate the field as the telescope tracks, alt-alt mounts, or altitude-altitude mounts, are designs similar to horizontal equatorial yoke mounts or Cardan suspension gimbals. This mount is an alternative to the mount that has the advantage of not having a blind spot near the zenith. It has the disadvantage of having all the mass, complexity and these mounts may include a third azimuth axis to rotate the entire mount into an orientation that allows smoother tracking. Slewing or mechanically driving the mounts polar axis in a direction to the Earths rotation allows the telescope to accurately follow the motion of the night sky. Tilting the polar axis adds a level of complexity to the mount, mechanical systems have to be engineered to support one or both ends of this axis. Designs such as German equatorial or cross axis mounts also need large counter weights to counterbalance the mass of the telescope, larger domes and other structures are also needed to cover the increased mechanical size and range of movement of equatorial mounts. Because of this, equatorial mounts become less viable in very large telescopes and have been pretty much replaced by altazimuth mounts for those applications, instead of the classical mounting using two axles, the mirror is supported by six extendable struts. This configuration allows moving the telescope in all six degrees of freedom
10.
Altazimuth mount
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An altazimuth or alt-azimuth mount is a simple two-axis mount for supporting and rotating an instrument about two perpendicular axes – one vertical and the other horizontal. Rotation about the vertical axis varies the azimuth of the direction of the instrument. Rotation about the horizontal axis varies the altitude of the pointing direction and these mounts are used, for example, with telescopes, cameras, radio antennas, heliostat mirrors, solar panels, and guns and similar weapons. Several names are given to this kind of mount, including altitude-azimuth, azimuth-elevation, a gun turret is essentially an alt-azimuth mount for a gun, and a standard camera tripod is an alt-azimuth mount as well. When used as a telescope mount, the biggest advantage of an alt-azimuth mount is the simplicity of its mechanical design. The primary disadvantage is its inability to follow objects in the night sky as the Earth spins on its axis. On the other hand, an equatorial mount only needs to be rotated about an axis, at a constant rate. Altazimuth mounts need to be rotated about both axes at variable rates, achieved via microprocessor based two-axis drive systems, to track equatorial motion and this imparts an uneven rotation to the field of view that also has to be corrected via a microprocessor based counter rotation system. The design also does not allow for the use of setting circles to locate astronomical objects although modern digital setting circles have removed this shortcoming. Another limitation is the problem of gimbal lock at zenith pointing, when tracking at elevations close to 90°, the azimuth axis must rotate very quickly, if the altitude is exactly 90°, the speed is infinite. Thus, altazimuth telescopes, although they can point in any direction, cannot track smoothly within a zenith blind spot, typical current applications of altazimuth mounts include, Research telescopes Mounts for very large telescopes. In the largest telescopes the mass and cost of a mount is prohibitive. The simple structure of an alt-azimuth mount allows significant cost reductions, an altazimuth mount also reduces the cost in the dome structure covering the telescope since the simplified motion of the telescope means the structure can be more compact. Altazimuth mounts are cheap and simple to use
11.
McDonald Observatory
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The McDonald Observatory is an astronomical observatory located near the unincorporated community of Fort Davis in Jeff Davis County, Texas, United States. The facility is located on Mount Locke in the Davis Mountains of West Texas, with facilities on Mount Fowlkes. The observatory is part of the University of Texas at Austin and it is an organized research unit of the College of Natural Sciences. The provision of the will was challenged by McDonalds relatives, but after a legal fight. The then-unnamed Otto Struve Telescope was dedicated on May 5,1939, McDonald Observatory was operated under contract by the University of Chicago until the 1960s, when control was transferred to the University of Texas at Austin under the direction of Harlan J. Smith. Directors Otto Struve Gerard Peter Kuiper Bengt Georg Daniel Strömgren William Wilson Morgan Harlan James Smith Frank N and it works closely with the astronomy department of the University of Texas at Austin while maintaining administrative autonomy. The high and dry peaks of the Davis Mountains make for some of the darkest and clearest night skies in the region, the Otto Struve Telescope, dedicated in 1939, was the first large telescope built at the observatory. It is located on Mt. Locke at an altitude of 2,070 m, the summit of Mt. Locke, accessed by Spur 78, is the highest point on Texas highways. The Harlan J. Smith Telescope, also on Mt. Locke, was completed in 1968, the Hobby-Eberly Telescope, dedicated in late 1997, is located on the summit of Mt. Fowlkes at 2,030 m above sea level. It is operated jointly by the University of Texas at Austin, Pennsylvania State University, Ludwig Maximilians University of Munich, as of 2012, the HET is tied with the similar Southern African Large Telescope as the fifth largest telescope in the world. However, its cost was about 20% that of other similarly-sized telescopes in use due to its optimization for spectrography. The McDonald Laser Ranging System operates a 0.76 m telescope on Mt. Fowlkes to perform satellite laser ranging, a 0.5 m Ritchey-Chretien reflector owned by Boston University on Mt. Locke is used for optical aeronomy. The 0.4 m Robotic Optical Transient Search Experiment reflector on Mt. Fowlkes is used to search for the signature of gamma-ray bursts. The 4.9 m Millimeter Wave Observatory radio telescope operated on Mt. Locke until 1988, MWO was a joint project between the UT Department of Astronomy and the Department of Electrical Engineering. The site of the antenna is now occupied by the BLOOMhouse, the UT School of Architectures entry in the 2007 Solar Decathlon. The observatory experiences a climate with cool, dry winters and hot. Coordinates,30. 70528°N104. 02333°W /30.70528, bash Visitors Center, located between Mt. Locke and Mt. Fowlkes, includes a café, gift shop, and interactive exhibit hall. The Visitors Center conducts daily live solar viewings in a large theater, special viewing nights, during which visitors can stay on-site and view directly through eyepieces on the 0.9 m, Struve, or Smith telescopes, are held on a reservation-only basis
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Segmented mirror
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A segmented mirror is an array of smaller mirrors designed to act as segments of a single large curved mirror. The segments can be spherical or asymmetric. They are used as objectives for large reflecting telescopes, to function, all the mirror segments have to be polished to a precise shape and actively aligned by a computer-controlled active optics system using actuators built into the mirror support cell. The concept and necessary technologies were developed under the leadership of Dr. There is a limit for primary mirrors made of a single rigid piece of glass. Such non-segmented, or monolithic mirrors can not be constructed larger than eight meters in diameter. The largest monolithic mirror in use are currently the two primary mirrors of the Large Binocular Telescope, each with a diameter of 8.4 meters, the use of segmented mirrors is therefore a key component for large-aperture telescopes. Using a monolithic mirror much larger than 5 meters is prohibitively expensive due to the cost of both the mirror, and the structure needed to support it. A mirror beyond that size would sag slightly under its own weight as the telescope was rotated to different positions. Segments are also easier to fabricate, transport, install, segmented mirrors do have the drawback that each segment may require some precise asymmetrical shape, and rely on a complicated computer-controlled mounting system. All of the segments also cause diffraction effects in the final image, some of the largest optical telescopes in the world use segmented primary mirrors. Both telescopes feature 10 m primary mirrors, Hobby-Eberly Telescope The HET is a 9. 2-meter telescope located at the McDonald Observatory, West Texas at an altitude of 2,026 m. Its primary mirror is constructed from 91 hexagonal segments, the telescopes main mirror is fixed at a 55 degree angle and can rotate around its base. A target is tracked by moving the instruments at the focus of the telescope, this access to about 70–81% of the sky at its location. Southern African Large Telescope The SALT is a 10-meter telescope dedicated on spectroscopy for most of its observing time. It shares similarities with the Hobby-Eberly Telescope and also consists of 91 hexagonal mirror segments, each 1 meter across and it is located close to the town of Sutherland in the semi-desert region of the Karoo, South Africa. It is a facility of the South African Astronomical Observatory, the national observatory of South Africa. Gran Telescopio Canarias Also known as the GranTeCan, the Canaries Great Telescope uses a total of 36 segmented mirrors
13.
Strehl ratios
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The Strehl ratio is a measure of the quality of optical image formation, originally proposed by Karl Strehl, after whom the term is named. Due to diffraction, even a system which is perfect according to geometrical optics will have a limited spatial resolution. In the usual case of a circular aperture, the point spread function which describes the image formed from an object with no spatial extent, is given by the Airy disk as illustrated here. For a circular aperture, the intensity found at the center of the Airy disk defines the point source image intensity required for a Strehl ratio of unity. An imperfect optical system using the physical aperture will generally produce a broader PSF in which the peak intensity is reduced according to the factor given by the Strehl ratio. Typically, as wavelength is increased, an optical system will have a broader PSF with a decreased peak intensity. The ratio is used to assess the quality of astronomical seeing in the presence of atmospheric turbulence. It is also used for the selection of short exposure images in the imaging method. That includes most telescopes and microscopes, but excludes most photographic systems, circle of confusion Fraunhofer diffraction Fraunhofer diffraction Huygens–Fresnel principle Optical transfer function Discussion page R. F
14.
Infrared
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It extends from the nominal red edge of the visible spectrum at 700 nanometers, to 1000000 nm. Most of the radiation emitted by objects near room temperature is infrared. Like all EMR, IR carries radiant energy, and behaves both like a wave and like its quantum particle, the photon, slightly more than half of the total energy from the Sun was eventually found to arrive on Earth in the form of infrared. The balance between absorbed and emitted infrared radiation has an effect on Earths climate. Infrared radiation is emitted or absorbed by molecules when they change their rotational-vibrational movements and it excites vibrational modes in a molecule through a change in the dipole moment, making it a useful frequency range for study of these energy states for molecules of the proper symmetry. Infrared spectroscopy examines absorption and transmission of photons in the infrared range, Infrared radiation is used in industrial, scientific, and medical applications. Night-vision devices using active near-infrared illumination allow people or animals to be observed without the observer being detected, Infrared thermal-imaging cameras are used to detect heat loss in insulated systems, to observe changing blood flow in the skin, and to detect overheating of electrical apparatuses. Thermal-infrared imaging is used extensively for military and civilian purposes, military applications include target acquisition, surveillance, night vision, homing, and tracking. Humans at normal body temperature radiate chiefly at wavelengths around 10 μm, Infrared radiation extends from the nominal red edge of the visible spectrum at 700 nanometers to 1 mm. This range of wavelengths corresponds to a range of approximately 430 THz down to 300 GHz. Below infrared is the portion of the electromagnetic spectrum. Sunlight, at a temperature of 5,780 kelvins, is composed of near thermal-spectrum radiation that is slightly more than half infrared. At zenith, sunlight provides an irradiance of just over 1 kilowatt per square meter at sea level, of this energy,527 watts is infrared radiation,445 watts is visible light, and 32 watts is ultraviolet radiation. Nearly all the radiation in sunlight is near infrared, shorter than 4 micrometers. On the surface of Earth, at far lower temperatures than the surface of the Sun, almost all thermal radiation consists of infrared in mid-infrared region, much longer than in sunlight. Of these natural thermal radiation processes only lightning and natural fires are hot enough to produce much visible energy, thermal infrared radiation also has a maximum emission wavelength, which is inversely proportional to the absolute temperature of object, in accordance with Wiens displacement law. Therefore, the band is often subdivided into smaller sections. Due to the nature of the blackbody radiation curves, typical hot objects, such as exhaust pipes, the three regions are used for observation of different temperature ranges, and hence different environments in space
15.
University of Arizona
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The University of Arizona is a public research university in Tucson, Arizona, United States. Founded in 1885, the UA was the first university in the Arizona Territory, the university operates two medical schools and is affiliated with the regions only academic medical centers. The university is home to the James E. Rogers College of Law and numerous other nationally ranked graduate. During the 2015-2016 academic year, there was an enrollment of 43,088 students. The University of Arizona is governed by the Arizona Board of Regents, the University of Arizona is one of the elected members of the Association of American Universities and is the only representative from the state of Arizona to this group. Known as the Arizona Wildcats, the teams are members of the Pac-12 Conference of the NCAA. UA athletes have won titles in several sports, most notably mens basketball, baseball. The official colors of the university and its teams are UA Red. After the passage of the Morrill Land-Grant Act of 1862, the push for a university in Arizona grew, the University of Arizona was approved by the Arizona Territorys Thieving Thirteenth Legislature in 1885, which also selected the city of Tucson to receive the appropriation to build the university. Tucson had hoped to receive the appropriation for the mental hospital. Tucson was largely disappointed with receiving what was viewed as an inferior prize. Construction of Old Main, the first building on campus, began on October 27,1887, and classes met for the first time in 1891 with 32 students in Old Main, which is still in use today. Because there were no schools in Arizona Territory, the university maintained separate preparatory classes for the first 23 years of operation. The University of Arizona offers 334 fields of study leading to bachelors, masters, doctoral, academic departments and programs are organized into colleges and schools. Currently, grades are given on a strict 4-point scale with A worth 4, B worth 3, C worth 2, D worth 1 and E worth zero points. In 2004, there were discussions with students and faculty that may lead the UA towards eventual usage of the grading system in future years. As of December 2015, the university uses the 4-points scale. The Center for World University Rankings in 2015 ranked Arizona 68th in the world, the 2015–16 Times Higher Education World University Rankings rated University of Arizona 163rd in the world and the 2016/17 QS World University Rankings ranked it 233rd
16.
University of Minnesota
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The University of Minnesota, Twin Cities is a public research university in Minneapolis and Saint Paul, Minnesota. The Minneapolis and St. Paul campuses are approximately 3 miles apart, and it is the oldest and largest campus within the University of Minnesota system and has the sixth-largest main campus student body in the United States, with 51,147 students in 2013–14. The university is the institution of the University of Minnesota system, and is organized into 19 colleges and schools, with sister campuses in Crookston, Duluth, Morris. Minnesota is one of Americas Public Ivy universities, which refers to top universities in the United States capable of providing a collegiate experience comparable with the Ivy League. Founded in 1851, The University of Minnesota is categorized as an R1 Doctoral University with the highest research activity in the Carnegie Classification of Institutions of Higher Education, Minnesota faculty, alumni, and researchers have won 25 Nobel Prizes and three Pulitzer Prizes. Notable University of Minnesota alumni include two Vice Presidents of the United States, Hubert Humphrey and Walter Mondale, and Bob Dylan, who received the 2016 Nobel Prize in Literature. The University of Minnesota Twin Cities is also a member of the Association of American Universities which is an association of the 62 leading research universities in the United States and Canada. In its 2017 edition, U. S. News & World Report ranked Minnesota 38th in their Best Global University Rankings, the Times Higher Education World University Rankings for 2015 ranks Minnesota 46th in the world. In 2015, Academic Ranking of World Universities ranked the university 11th in the world for mathematics, the University of Minnesota is ranked 14 over-all among the nations top research universities by the Center for Measuring University Performance. The U. S. News & World Reports 2016 rankings placed the program of the University as the 69th-best National University in the United States. Additionally, nineteen of the Universitys graduate-school departments have been ranked in the nations top-twenty by the U. S. National Research Council, in both 2008 and 2012 U. S. News & World Report ranked the College of Pharmacy 2nd in the nation. 2016 U. S. News & Report now rank the College of Pharmacy 2nd in the nation. In 2011, U. S. News & World Report ranked the School of Public Health 8th in the nation, the University of Minnesota ranked 19th in NIH funding in 2008. Minnesota is listed as a Public Ivy in 2001 Greenes Guides The Public Ivies, the university developed Gopher, a precursor to the World Wide Web which used hyperlinks to connect documents across computers on the internet. However, the produced by CERN was favored by the public since it was freely distributed. The University also houses the Charles Babbage Institute, a research, the department has strong roots in early days of supercomputing with Seymour Cray of Cray supercomputers. Notable faculty of the department are Yousef Saad, Vipin Kumar, Jaideep Srivastava, John Riedl, some notable alumni of the department are Ed Chi, Imrich Chlamtac, Leah Culver, Jeff Dean, Mark P. McCahill, Arvind Mithal, and Calvin Mooers. Puffed rice - Alexander P. Anderson led to the discovery of puffed rice, transistorized cardiac pacemaker - Earl Bakken founded Medtronic, where he developed the first external, battery-operated, transistorized, wearable artificial pacemaker in 1957
17.
University of Notre Dame
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The University of Notre Dame du Lac is a Catholic research university located adjacent to South Bend, Indiana, in the United States. In French, Notre Dame du Lac means Our Lady of the Lake and refers to the patron saint. The main campus covers 1,250 acres in a setting and it contains a number of recognizable landmarks, such as the Golden Dome, the Word of Life mural. The school was founded on November 26,1842, by Father Edward Sorin, CSC, Today, many Holy Cross priests continue to work for the university, including the president of the university. Notre Dame is a large, four-year, highly residential research university, undergraduate students are organized into four colleges, and the Architecture School. The latter is known for teaching New Classical Architecture and for awarding the globally renowned annual Driehaus Architecture Prize, the university offers over 50 foreign study abroad yearlong programs and over 15 summer programs. It maintains a system of libraries, cultural venues, artistic and scientific museums, including the Hesburgh Library and the Snite Museum of Art. Over 80% of the universitys 8,000 undergraduates live on campus in one of 29 single-sex residence halls, each with its own traditions, legacies, events, the university counts approximately 120,000 alumni. The universitys athletic teams are members of the NCAA Division I and are known collectively as the Fighting Irish, other ND sport teams, chiefly in the Atlantic Coast Conference, have accumulated 16 national championships. The Notre Dame Victory March is often regarded as the most famous, started as a small all-male institution in 1842 and charter in 1844, Notre Dame reached international fame at the beginning of the 20th century. Ever since, the University has seen growth, and under the leadership of the next two presidents, Rev. Malloy and Rev. Jenkins, many infrastructure and research expansions have been completed. In 1842, the Bishop of Vincennes, Célestine Guynemer de la Hailandière, offered land to Father Edward Sorin of the Congregation of Holy Cross, on the condition that he build a college in two years. Sorin arrived on the site with eight Holy Cross brothers from France and Ireland on November 26,1842 and he soon erected additional buildings, including the Old College, the first church, and the first main building. They immediately acquired two students and set about building additions to the campus, Notre Dame began as a primary and secondary school, but soon received its official college charter from the Indiana General Assembly on January 15,1844. Under the charter the school is named the University of Notre Dame du Lac. Because the university was only for male students, the female-only Saint Marys College was founded by the Sisters of the Holy Cross near Notre Dame in 1844. The first degrees from the college were awarded in 1849, the university was expanded with new buildings to accommodate more students and faculty. With each new president, new programs were offered and new buildings built to accommodate them
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University of Virginia
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The University of Virginia, frequently referred to simply as Virginia, is a public research university and the flagship for the Commonwealth of Virginia. Founded in 1819 by Declaration of Independence author Thomas Jefferson, UVA is known for its foundations, student-run honor code. UNESCO designated UVA as Americas first and only collegiate World Heritage Site in 1987, the university was established in 1819, and its original governing Board of Visitors included Thomas Jefferson, James Madison, and James Monroe. Monroe was the sitting President of the United States at the time of its foundation, former Presidents Jefferson and Madison were UVAs first two rectors and the Academical Village and Jefferson conceived and designed the original courses of study. The universitys research endeavors are highly recognized, in 2015, Science honored UVA faculty for discovering two of its top 10 annual scientific breakthroughs, from the fields of Medicine and Psychology. UVA is one of 62 institutions in the Association of American Universities and it is the only AAU member university in Virginia. UVA is classified as a Research University with Very High Research by the Carnegie Foundation, the university was the first non-founding member, and the first university of the American South, to attain AAU membership in 1904. UVAs academic strength is broad, with 121 majors across the eight undergraduate, students compete in 26 collegiate sports and UVA leads the Atlantic Coast Conference in mens NCAA team national championships with 17. UVA is second in womens NCAA titles with 7, UVA was awarded the Capital One Cup in 2015 after fielding the top overall mens athletics programs in the nation. Students come to attend the university in Charlottesville from all 50 states and 147 countries, the historic 1, 682-acre campus is internationally protected by UNESCO and considered one of the most beautiful collegiate grounds in the country. UVA additionally maintains 2,913 acres southeast of the city, the university also manages the College at Wise in Southwest Virginia, and until 1972 operated George Mason University and the University of Mary Washington in Northern Virginia. In 1817, three Presidents and Chief Justice of the United States Supreme Court John Marshall joined 24 other dignitaries at a meeting held in the Mountain Top Tavern at Rockfish Gap, after some deliberation, they selected nearby Charlottesville as the site of the new University of Virginia. Farmland just outside Charlottesville was purchased from James Monroe by the Board of Visitors as Central College, the school laid its first buildings cornerstone late in that same year, and the Commonwealth of Virginia chartered the new university on January 25,1819. John Hartwell Cocke collaborated with James Madison, Monroe, and Joseph Carrington Cabell to fulfill Jeffersons dream to establish the university, Cocke and Jefferson were appointed to the building committee to supervise the construction. The universitys first classes met on March 7,1825, another innovation of the new university was that higher education would be separated from religious doctrine. Jefferson opined to philosopher Thomas Cooper that a professorship of theology should have no place in our institution, Jefferson was intimately involved in the university to the end, hosting Sunday dinners at his Monticello home for faculty and students until his death. Thus, he eschewed mention of his accomplishments, such as the Louisiana Purchase. This was a source of frustration for Jefferson, who assembled the students during the schools first year, on October 3,1825, to such behavior
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Max Planck Institute for Astronomy
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For similarly named astronomy institutes, see, Institute of Astronomy. The Max-Planck-Institut für Astronomie is an institute of the Max Planck Society. It is located in Heidelberg, Baden-Württemberg, Germany near the top of the Koenigstuhl, the institute was founded in 1967. Its founding directors were H. Elsässer, and G. Munch, the current directors are Hans-Walter Rix and Thomas Henning. G. H. Herbig, Karl-Heinz Böhm, Immo Appenzeller, Willy Benz, current research interests include formation of planets, stars in the group of Thomas Henning and galaxies and cosmology in the group of Hans-Walter Rix. D. in astrophysics. The school is run in cooperation with the University of Heidelberg, HIP13044 b Homepage of the Max Planck Institute for Astronomy Homepage of the International Max Planck Research School for Astronomy and Cosmic Physics
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Leibniz Institute for Astrophysics Potsdam
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Leibniz Institute for Astrophysics Potsdam is a German research institute. It is the successor of the Berlin Observatory founded in 1700, the latter was the worlds first observatory to emphasize explicitly the research area of astrophysics. The AIP was founded in 1992, in a following the German Reunification. The AIP is privately funded and member of the Leibniz Association, the key topics of the AIP are cosmic magnetic fields on various scales and extragalactic astrophysics. Astronomical and astrophysical fields studied at the AIP range from solar and stellar physics to stellar, the institute also develops research technology in the fields of spectroscopy and robotic telescopes. Furthermore, work on several projects are carried out at the AIP. The history of astronomy in Potsdam really began in Berlin in 1700, initiated by Gottfried W. Leibniz, on July 11,1700 the Brandenburgische Societät was founded by the elector Friedrich III in Berlin. Two months earlier the national calendar monopoly provided the funding for an observatory, by May 18 the first director, Gottfried Kirch, had been appointed. This happened in a hurry, because the profits from the basic calendar, calculated and sold by the observatory. This kind of financing existed until the beginning of the 19th century, alexander von Humboldt was then promoting astronomy by his famous Kosmos lectures in 1827–28. He played an important role in providing the funds for both observatory and instruments, the Berlin Observatory became known worldwide when Johann Gottfried Galle discovered the planet Neptune in 1846. The last two events took place when Wilhelm Julius Foerster was director of the observatory, which was meanwhile attached to the University of Berlin. He prepared the basis for the observatories in Potsdam, in 1874 the foundation of the AOP on the Telegrafenberg. In the middle of the 19th century spectral analysis was developed by Gustav Kirchhoff and it enabled the acquisition of information on the physical parameters and chemical abundances of stars, by the spectral analysis of their light. This idea was extended to the whole of astrophysics. The site of the observatory was chosen on a hill south of Potsdam, the Telegrafenberg, on which had been, from 1832 to 1848, on 1 July 1874 the AOP was founded. The construction work started in 1876, the observatory building. The AOP was managed by a board of directors comprising Wilhelm Julius Foerster, Gustav Kirchhoff, in 1882 Carl Hermann Vogel was appointed as sole director of the observatory
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Max Planck Institute for Extraterrestrial Physics
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The Max Planck Institute for Extraterrestrial Physics is a Max Planck Institute, located in Garching, near Munich, Germany. The Max Planck Institute for Extraterrestrial Physics was founded as sub-institute in 1963, the scientific activities of the institute are mostly devoted to astrophysics with telescopes orbiting in space. A large amount of the resources are spent for studying black holes in the galaxy, the Max-Planck-Institute for extraterrestrial physics was preceded by the department for extraterrestrial physics in the Max-Planck-Institute for physics and astrophysics. This department was established by Professor Reimar Lüst on October 23,1961, a Max-Planck Senate resolution transformed this department into a sub-institute of the Max-Planck-Institute for Physics and Astrophysics on May 15,1963. Professor Lüst was appointed director of the Institute, another Senate resolution on March 8,1991 finally established MPE as an autonomous institute within the Max-Planck-Gesellschaft. It is dedicated to the experimental and theoretical exploration of the space outside of earth as well as astrophysical phenomena, the former independent X-ray and Gamma-ray departments are merged into the new high-energy astrophysics department. This department was established by Professor Reimar Lüst on October 23,1961, a Max-Planck Senate resolution transformed this department into a sub-institute of the Max-Planck-Institut für Physik und Astrophysik on May 15,1963. Professor Lüst was appointed Director of the Institute, another Senate resolution on March 8,1991 finally established MPE as an autonomous institute within the Max-Planck-Gesellschaft. It is dedicated to the experimental and theoretical exploration of the space outside of earth as well as astrophysical phenomena, a continuous reorientation to new, promising fields of research and the appointment of new members ensures steady advancement. Among the 29 employees of the Institute when it was founded in 1963 were 9 scientists and 1 Ph. D. student. Twelve years later in 1975 the number of employees had grown to 180 with 55 scientists and 13 Ph. D. students and it is noteworthy that permanent positions at the institute have not increased since 1973 - despite its celebrated scientific achievements. The increasingly complex tasks and international obligations have been maintained by staff members with positions having limited duration. Because the Institute has assumed a position in astronomy internationally. The number of guests increased from 12 in 1974 to a maximum of 72 in 2000. In recent years MPE has hosted an average of about 50 guest scientists each year, during the early years the scientific work at the Institute concentrated on the investigation of extraterrestrial plasmas and the magnetosphere of the earth. This work was performed with measurements of particles and electromagnetic fields as well as a specially developed ion-cloud technique using sounding rockets and these observations and inferences therefrom are the subject matter of infra-red astronomy as well as X-ray- and gamma-ray-astronomy. In addition to more than 100 rockets, a number of high-altitude balloons have been used to carry experiments to high altitudes. Since the 1990s, satellites have become the preferred observation platforms because of their favorable observation-time/cost ratio, nevertheless, high-flying observation airplanes and ground-based telescopes are also used to obtain data especially for optical and near-infrared observations
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Munich
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Munich is the capital and largest city of the German state of Bavaria, on the banks of River Isar north of the Bavarian Alps. Munich is the third largest city in Germany, after Berlin and Hamburg, the Munich Metropolitan Region is home to 5.8 million people. According to the Globalization and World Rankings Research Institute Munich is considered an alpha-world city, the name of the city is derived from the Old/Middle High German term Munichen, meaning by the monks. It derives from the monks of the Benedictine order who ran a monastery at the place that was later to become the Old Town of Munich, Munich was first mentioned in 1158. From 1255 the city was seat of the Bavarian Dukes, black and gold—the colours of the Holy Roman Empire—have been the citys official colours since the time of Ludwig the Bavarian, when it was an imperial residence. Following a final reunification of the Wittelsbachian Duchy of Bavaria, previously divided and sub-divided for more than 200 years, like wide parts of the Holy Roman Empire, the area recovered slowly economically. In 1918, during the German Revolution, the house of Wittelsbach, which governed Bavaria since 1180, was forced to abdicate in Munich. In the 1920s, Munich became home to political factions, among them the NSDAP. During World War II, Munich was heavily bombed and more than 50% of the entire city, the postwar period was characterised by American occupation until 1949 and a strong increase of population and economic power during the years of the Wirtschaftswunder after 1949. The city is home to corporations like BMW, Siemens, MAN, Linde, Allianz and MunichRE as well as many small. Munich is home to national and international authorities, major universities, major museums. Its numerous architectural attractions, international events, exhibitions and conferences. Munich is one of the most prosperous and fastest growing cities in Germany and it is a top-ranked destination for migration and expatriate location, despite being the municipality with the highest density of population in Germany. Munich nowadays hosts more than 530,000 people of foreign background, the year 1158 is assumed to be the foundation date, which is the earliest date the city is mentioned in a document. The document was signed in Augsburg, by that time the Guelph Henry the Lion, Duke of Saxony and Bavaria, had built a bridge over the river Isar next to a settlement of Benedictine monks—this was on the Old Salt Route and a toll bridge. In 1175, Munich was officially granted city status and received fortification, in 1180, with the trial of Henry the Lion, Otto I Wittelsbach became Duke of Bavaria and Munich was handed over to the Bishop of Freising. In 1240, Munich was transferred to Otto II Wittelsbach and in 1255, Duke Louis IV, a native of Munich, was elected German king in 1314 and crowned as Holy Roman Emperor in 1328. He strengthened the position by granting it the salt monopoly
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Max Planck Institute for Radio Astronomy
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The Max Planck Institute for Radio Astronomy is located in Bonn, Germany. It is one of 80 institutes in the Max Planck Society, in 1972 the 100-m radio telescope in Effelsberg was opened. The institute building was enlarged in 1983 and 2002, the southern wing of the whole complex is occupied by the Argelander Institute of Astronomy of the University of Bonn. The Institute has three research groups, each with its own Director - Fundamental Physics, VLBI and Millimetre Astronomy. The International Max Planck Research School for Astronomy and Astrophysics is a highly competitive-entry graduate program offering a Ph. D, the school is run in cooperation with the University of Bonn and University of Cologne. Homepage of the Max Planck Institute for Radio Astronomy Homepage of the International Max Planck Research School for Astronomy and Astrophysics
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Bonn
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The Federal City of Bonn is a city on the banks of the Rhine in the German state of North Rhine-Westphalia, with a population of 311,287. About 24 km south-southeast of Cologne, Bonn is in the southernmost part of the Rhine-Ruhr region, Germanys largest metropolitan area, the title of Federal City reflects its particular political status within Germany. Founded in the 1st century BC as a Roman settlement, Bonn is one of Germanys oldest cities, from 1597 to 1794, Bonn was the capital of the Electorate of Cologne, and residence of the Archbishops and Prince-electors of Cologne. Composer Ludwig van Beethoven was born here in 1770, from 1949 to 1990, Bonn was the capital of West Germany, and it is here where Germanys present constitution, the Grundgesetz, was declared in 1949. From 1990 to 1999, Bonn served as the seat of government, two DAX-listed corporations, Deutsche Post DHL and Deutsche Telekom, have headquarters in Bonn. The city is the location of the University of Bonn, spanning an area of more 141.2 km2 on both sides of the River Rhine, almost three quarters of the city lie on the rivers left bank. To the south and to the west, Bonn is bordering the Eifel region which encompasses the Rhineland Nature Park, to the north, Bonn borders the Cologne Lowland. Natural borders are constituted by the River Sieg to the north-east, the largest extension of the city in north-south dimensions is 15 km and 12.5 km in west-east dimensions. The city borders have a length of 61 km. The geographical centre of Bonn is the Bundeskanzlerplatz in Bonn-Gronau, the German state of North Rhine-Westphalia is divided into five governmental districts, and Bonn is part of the governmental district of Cologne. Within this governmental district, the city of Bonn is an district in its own right. The urban district of Bonn is then divided into four administrative municipal districts. These are Bonn, Bonn-Bad Godesberg, Bonn-Beuel and Bonn-Hardtberg, in 1969, the independent towns of Bad Godesberg and Beuel as well as several villages were incorporated into Bonn, resulting in a city more than twice as large as before. In the south of the Cologne lowland in the Rhine valley, the history of the city dates back to Roman times. In about 12 BC, the Roman army appears to have stationed a small unit in what is presently the historical centre of the city, even earlier, the army had resettled members of a Germanic tribal group allied with Rome, the Ubii, in Bonn. The Latin name for that settlement, Bonna, may stem from the population of this and many other settlements in the area. The Eburoni were members of a tribal coalition effectively wiped out during the final phase of Caesars War in Gaul. After several decades, the gave up the small camp linked to the Ubii-settlement
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Ohio State University
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The Ohio State University, commonly referred to as Ohio State or OSU, is a large, primarily residential, public university in Columbus, Ohio. Founded in 1870 as a land-grant university and ninth university in Ohio with the Morrill Act of 1862, Hayes, and in 1878 the Ohio General Assembly passed a law changing the name to The Ohio State University. It has since grown into the third-largest university campus in the United States, along with its main campus in Columbus, Ohio State also operates a regional campus system with regional campuses in Lima, Mansfield, Marion, Newark, and Wooster. Ohio State athletic teams compete in Division I of the NCAA and are known as the Ohio State Buckeyes, athletes from Ohio State have won 100 Olympic medals. The university is a member of the Big Ten Conference for the majority of sports, the Ohio State mens ice hockey program competes in the Big Ten Conference, while its womens hockey program competes in the Western Collegiate Hockey Association. In addition, the OSU mens volleyball team is a member of the Midwestern Intercollegiate Volleyball Association, OSU is one of only 14 universities that plays Division I FBS football and Division I ice hockey. As of August 2015, the university had awarded a total of 714,512 degrees, alumni and former students have gone on to prominent careers in government, business, science, medicine, education, sports, and entertainment. Championed by the Republican stalwart Governor Rutherford B, Hayes, the Ohio State University was founded in 1870 as a land-grant university under the Morrill Act of 1862 as the Ohio Agricultural and Mechanical College. The school was originally within a community on the northern edge of Columbus. The university opened its doors to 24 students on September 17,1873, in 1878, the first class of six men graduated. The first woman graduated the following year, also in 1878, in light of its expanded focus, the Ohio legislature changed the name to the now-familiar The Ohio State University, with The as part of its official name. Ohio State began accepting students in the 1880s, and in 1891. It would later acquire colleges of medicine, dentistry, optometry, veterinary medicine, commerce, in 1916, Ohio State was elected into membership in the Association of American Universities. Michael V. Drake, former chancellor of the University of California, Irvine, in an attack against the campus on November 28,2016, an unrelated fluorine leak was called in for Watts Hall, resulting in the evacuation of the building to an outside courtyard. As firetrucks began to depart, Abdul Razak Ali Artan drove into the crowd, then emerged, the attack was stopped in under two minutes by OSU Police Officer Alan Horujko, who witnessed the attack after responding to the reported gas leak, and who shot and killed Artan. The universitys Buckeye Alert system was triggered and the campus was placed on lockdown, Ten were transported to local hospitals and one suspect was killed according to multiple sources. Local law enforcement and the FBI launched an investigation, according to authorities, Artan was inspired by terrorist propaganda from the Islamic State and radical Muslim cleric Anwar al-Awlaki. Ohio States 1, 764-acre main campus is about 2.5 miles north of the citys downtown, the historical center of campus is the Oval, quad of about 11 acres
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Binoculars
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Binoculars or field glasses are two telescopes mounted side-by-side and aligned to point in the same direction, allowing the viewer to use both eyes when viewing distant objects. Most are sized to be held using both hands, although sizes vary widely from opera glasses to large pedestal mounted military models. Almost from the invention of the telescope in the 17th century the advantages of mounting two of them side by side for binocular vision seems to have been explored, most early binoculars used Galilean optics, that is, they used a convex objective and a concave eyepiece lens. The Galilean design has the advantage of presenting an image but has a narrow field of view and is not capable of very high magnification. This type of construction is used in very cheap models. They also have large exit pupils making centering less critical and the field of view works well in those applications. These are typically mounted on a frame or custom-fit onto eyeglasses. An improved image and higher magnification is achieved in binoculars employing Keplerian optics, since the Keplerian configuration produces an inverted image, different methods were used to turn the image right way up. In aprismatic binoculars with Keplerian optics each tube has one or two additional lenses between the objective and the ocular and these lenses are used to erect the image. The binoculars with erecting lenses have a disadvantage, their length is too long. Such binoculars were popular in the 1800s, but became obsolete shortly after the Karl Zeiss company introduced improved prism binoculars in the 1890s, Optical prisms added to the design are another way to turn the image right way up, usually in a Porro prism or roof-prisms design. Porro prism binoculars are named after Italian optician Ignazio Porro who patented this image erecting system in 1854, Binoculars of this type use a Porro prism in a double prism Z-shaped configuration to erect the image. This feature results in binoculars that are wide, with lenses that are well separated. Thus, the size of binoculars is reduced, Binoculars using roof prisms may have appeared as early as the 1870s in a design by Achille Victor Emile Daubresse. Most roof prism binoculars use either the Abbe-Koenig prism or the Schmidt-Pechan prism designs to erect the image and they have objective lenses that are approximately in line with the eyepieces. Roof-prisms designs create an instrument that is narrower and more compact than Porro prisms, there is also a difference in image brightness. Roof-prisms designs also require tighter tolerances for alignment of their optical elements and this adds to their expense since the design requires them to use fixed elements that need to be set at a high degree of collimation at the factory. Porro prisms binoculars occasionally need their prism sets to be re-aligned to bring them into collimation, the fixed alignment in roof-prism designs means the binoculars normally will not need re-collimation
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Active optics
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Without active optics, the construction of 8 metre class telescopes is not possible, nor would telescopes with segmented mirrors be feasible. Active optics is not to be confused with adaptive optics, which operates at a shorter timescale, most modern telescopes are reflectors, with the primary element being a very large mirror. Historically, primary mirrors were quite thick in order to maintain the correct figure in spite of forces tending to deform it, like wind. This limited their maximum diameter to 5 or 6 metres, such as Palomar Observatorys Hale telescope, a new generation of telescopes built since the 1980s use thin, lighter weight mirrors instead. They are too thin to maintain themselves rigidly in the correct shape, the actuators apply variable forces to the mirror body to keep the reflecting surface in the correct shape over repositioning. The telescope may also be segmented into multiple smaller mirrors, which reduce the sagging due to weight that occurs for large, the combination of actuators, an image quality detector, and a computer to control the actuators to obtain the best possible image, is called active optics. The name active optics means that the system keeps a mirror in its optimal shape against environmental forces such as wind, sag, thermal expansion, Active optics compensate for distorting forces that change relatively slowly, roughly on timescales of seconds. The telescope is therefore actively still, in its optimal shape, Active optics should not be confused with adaptive optics, which operates on a much shorter timescale to compensate for atmospheric effects, rather than for mirror deformation. The influences that active optics compensate are intrinsically slower and have an amplitude in aberration. Adaptive optics on the other hand corrects for atmospheric distortions that affect the image at 100–1000 Hz and these corrections need to be much faster, but also have smaller amplitude. Because of this, adaptive optics uses smaller corrective mirrors and this used to be a separate mirror not integrated in the telescopes light path, but nowadays this can be the second, third or fourth mirror in a telescope. Complicated laser set-ups and interferometers can also be actively stabilized, the system can be sped up or made more noise-immune by using a PID controller. For pulsed lasers the controller should be locked to the repetition rate, a continuous pilot beam can be used to allow for up to 10 kHz bandwidth of stabilization for low repetition rate lasers. Sometimes Fabry–Pérot interferometers have to be adjusted in length to pass a given wavelength, therefore, the reflected light is extracted by means of a Faraday rotator and a polarizer. Long optical cavities are very sensitive to the mirror alignment, a control circuit can be used to peak power. One possibility is to perform small rotations with one end mirror, if this rotation is about the optimum position, no power oscillation occurs. Any beam pointing oscillation can be removed using the steering mechanism mentioned above. X-ray active optics, using actively deformable grazing incidence mirrors, are also being investigated, adaptive optics – faster technology for smaller aberrations
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Adaptive optics
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Adaptive optics works by measuring the distortions in a wavefront and compensating for them with a device that corrects those errors such as a deformable mirror or a liquid crystal array. Adaptive optics should not be confused with active optics, which works on a timescale to correct the primary mirror geometry. Adaptive optics was first envisioned by Horace W, some of the initial development work on adaptive optics was done by the US military during the Cold War and was intended for use in tracking Soviet satellites. The simplest form of adaptive optics is tip-tilt correction, which corresponds to correction of the tilts of the wavefront in two dimensions and this is performed using a rapidly moving tip–tilt mirror that makes small rotations around two of its axes. A significant fraction of the aberration introduced by the atmosphere can be removed in this way, tip–tilt mirrors are effectively segmented mirrors having only one segment which can tip and tilt, rather than having an array of multiple segments that can tip and tilt independently. Due to the simplicity of such mirrors and having a large stroke, meaning they have large correcting power, most AO systems use these, first. Higher order aberrations may then be corrected with deformable mirrors, when light from a star or another astronomical object enters the Earths atmosphere, atmospheric turbulence can distort and move the image in various ways. Visual images produced by any larger than approximately 20 centimeters are blurred by these distortions. In order to perform adaptive optics correction, the shape of the incoming wavefronts must be measured as a function of position in the aperture plane. The mean wavefront perturbation in each pixel is calculated and this pixelated map of the wavefronts is fed into the deformable mirror and used to correct the wavefront errors introduced by the atmosphere. The deformable mirror corrects incoming light so that the images appear sharp, because a science target is often too faint to be used as a reference star for measuring the shape of the optical wavefronts, a nearby brighter guide star can be used instead. This severely limits the application of the technique for astronomical observations, another major limitation is the small field of view over which the adaptive optics correction is good. As the angular distance from the star increases, the image quality degrades. A technique known as adaptive optics uses several deformable mirrors to achieve a greater field of view. An alternative is the use of a beam to generate a reference light source in the atmosphere. LGSs come in two flavors, Rayleigh guide stars and sodium guide stars, Rayleigh guide stars work by propagating a laser, usually at near ultraviolet wavelengths, and detecting the backscatter from air at altitudes between 15–25 km. Sodium guide stars use laser light at 589 nm to excite sodium atoms higher in the mesosphere and thermosphere, which then appear to glow. The LGS can then be used as a wavefront reference in the way as a natural guide star – except that natural reference stars are still required for image position information
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Interferometry
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Interferometry is a family of techniques in which waves, usually electromagnetic waves, are superimposed causing the phenomenon of interference in order to extract information. Interferometers are widely used in science and industry for the measurement of small displacements, refractive index changes, in an interferometer, light from a single source is split into two beams that travel different optical paths, then combined again to produce interference. The resulting interference fringes give information about the difference in path length, waves which are not completely in phase nor completely out of phase will have an intermediate intensity pattern, which can be used to determine their relative phase difference. Most interferometers use light or some form of electromagnetic wave. Typically a single incoming beam of coherent light will be split into two beams by a beam splitter. Each of these beams travels a different route, called a path, the path difference, the difference in the distance traveled by each beam, creates a phase difference between them. It is this phase difference that creates the interference pattern between the initially identical waves. If a single beam has been split along two paths, then the difference is diagnostic of anything that changes the phase along the paths. This could be a change in the path length itself or a change in the refractive index along the path. As seen in Fig. 2a and 2b, the observer has a view of mirror M1 seen through the beam splitter. The fringes can be interpreted as the result of interference between light coming from the two virtual images S1 and S2 of the original source S, the characteristics of the interference pattern depend on the nature of the light source and the precise orientation of the mirrors and beam splitter. In Fig. 2a, the elements are oriented so that S1 and S2 are in line with the observer. Use of white light will result in a pattern of colored fringes, the central fringe representing equal path length may be light or dark depending on the number of phase inversions experienced by the two beams as they traverse the optical system. Interferometers and interferometric techniques may be categorized by a variety of criteria, In homodyne detection, the phase difference between the two beams results in a change in the intensity of the light on the detector. The resulting intensity of the light after mixing of two beams is measured, or the pattern of interference fringes is viewed or recorded. Most of the interferometers discussed in this article fall into this category, the heterodyne technique is used for shifting an input signal into a new frequency range as well as amplifying a weak input signal. A weak input signal of frequency f1 is mixed with a reference frequency f2 from a local oscillator. The nonlinear combination of the input signals creates two new signals, one at the sum f1 + f2 of the two frequencies, and the other at the difference f1 − f2 and these new frequencies are called heterodynes
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Leonardo S.p.A.
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Leonardo S. p. A. formerly Leonardo-Finmeccanica and Finmeccanica, is an Italian multinational aerospace, defence and security company headquartered in Rome in Italy and with operations worldwide. It is the ninth-largest defence contractor in the based on applicable 2014 revenues. The company is owned by the Italian government through the Ministry of Economy and Finance. On 1 January 2016, Leonardo-Finmeccanica became an industrial company by integrating the activities of its subsidiaries AgustaWestland, Alenia Aermacchi, Selex ES, Oto Melara. Leonardo-Finmeccanica is listed on the Borsa Italiana and is a constituent of the FTSE MIB, the company changed its name to Leonardo S. p. A. on 1 January 2017, after the Italian inventor Leonardo Da Vinci. The company was established in 1948 as a subholding for mechanical industry of state owned IRI, Finmeccanica has held for years some historic Italian enterprises, such as Alfa Romeo, Aeritalia and Ansaldo. In 1989 an internal IRI reorganization process brought STET electronic enterprises to Finmeccanica, Finmeccanica, which was previously fully state owned by IRI, went under a privatization process in 1993, when it was listed in Milan Borsa Italiana. In 1992 Finmeccanicas Agusta became a 32% partner in NHIndustries, the contractor for NH90 helicopter. In July 2000 Finmeccanica and the British GKN agreed to merge their respective helicopter subsidiaries to form AgustaWestland, in July 2003 Finmeccanica and BAE Systems announced their intention to set up three joint venture companies, to be collectively known as Eurosystems. These companies would have pooled the avionics, C4ISTAR and communications businesses of the two companies, in March 2007 BAE Systems sold its 25% share to Finmeccanica for €400 million. In January 2013 the company merged with Finmeccanicas other defence electronics companies, SELEX Elsag and SELEX Sistemi Integrati, in May 2008 Finmeccanica announced its intention to purchase the U. S. defense contractor DRS Technologies for nearly $5.2 billion. On 22 October 2008 the sale of DRS Technologies was finalized, during 2011–2013, Finmeccanica emails were published by WikiLeaks and Finmeccanica was subject to judicial inquiries on several fronts and management changes. On 12 February 2013, the executive, Giuseppe Orsi, was arrested on corruption charges. Prosecutors alleged that he paid bribes to ensure the sale of 12 helicopters to the Indian government, in July 2013, the Letta government appointed former police chief Giovanni De Gennaro as Chairman of Finmeccanica. In December 2013 Finmeccanica sold 39. 55% of its capital in Ansaldo Energia to Fondo Strategico Italiano. The remaining 15% of Finmeccanicas share will be sold by December 31,2017, the goal was to create a more cohesive and efficient group in which all processes are centralized and integrated and can interact more effectively. This encompasses the 100% owned companies of the aerospace and defence business being transformed into seven new Finmeccanica divisions. At the end of 2014, Finmeccanica transferred its stake in BredaMenarinibus to the newco Industria Italiana Autobus, thereby taking a further step in the Groups portfolio rationalization process
31.
Milan
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Milan is a city in Italy, capital of the Lombardy region, and the most populous metropolitan area and the second most populous comune in Italy. The population of the city proper is 1,351,000, Milan has a population of about 8,500,000 people. It is the industrial and financial centre of Italy and one of global significance. In terms of GDP, it has the largest economy among European non-capital cities, Milan is considered part of the Blue Banana and lies at the heart of one of the Four Motors for Europe. Milan is an Alpha leading global city, with strengths in the arts, commerce, design, education, entertainment, fashion, finance, healthcare, media, services, research, and tourism. Its business district hosts Italys Stock Exchange and the headquarters of the largest national and international banks, the city is a major world fashion and design capital, well known for several international events and fairs, including Milan Fashion Week and the Milan Furniture Fair. The city hosts numerous cultural institutions, academies and universities, with 11% of the national total enrolled students, Milans museums, theatres and landmarks attract over 9 million visitors annually. Milan – after Naples – is the second Italian city with the highest number of accredited stars from the Michelin Guide, the city hosted the Universal Exposition in 1906 and 2015. Milan is home to two of Europes major football teams, A. C. Milan and F. C. Internazionale, the etymology of Milan is uncertain. One theory holds that the Latin name Mediolanum comes from the Latin words medio, however, some scholars believe lanum comes from the Celtic root lan, meaning an enclosure or demarcated territory in which Celtic communities used to build shrines. Hence, Mediolanum could signify the central town or sanctuary of a Celtic tribe, indeed, the name Mediolanum is borne by about sixty Gallo-Roman sites in France, e. g. Saintes and Évreux. Alciato credits Ambrose for his account, around 400 BC, the Celtic Insubres settled Milan and the surrounding region. In 222 BC, the Romans conquered the settlement, renaming it Mediolanum, Milan was eventually declared the capital of the Western Roman Empire by Emperor Diocletian in 286 AD. Diocletian chose to stay in the Eastern Roman Empire and his colleague Maximianus ruled the Western one, immediately Maximian built several monuments, such as a large circus 470 m ×85 m, the Thermae Herculeae, a large complex of imperial palaces and several other buildings. With the Edict of Milan of 313, Emperor Constantine I guaranteed freedom of religion for Christians, after the city was besieged by the Visigoths in 402, the imperial residence was moved to Ravenna. In 452, the Huns overran the city, in 539, the Ostrogoths conquered and destroyed Milan during the Gothic War against Byzantine Emperor Justinian I. In the summer of 569, a Teutonic tribe, the Lombards, conquered Milan, some Roman structures remained in use in Milan under Lombard rule. Milan surrendered to the Franks in 774 when Charlemagne took the title of King of the Lombards, the Iron Crown of Lombardy dates from this period
32.
San Carlos Apache Indian Reservation
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On December 14,1872, President U. S. Grant established the San Carlos Apache Reservation. The government gave various religious groups responsibility for managing the new reservations, the U. S. Army showed both animosity toward the Indians and disdain for the civilian Indian Agents. Politicians also ignored political differences and military alliances and tried to apply a strategy to deal with the “Indian problem”. As a result, tribal friends and foes were forced to live in proximity to one another. Meanwhile, the Apaches were supposed to be fed and housed by their caretakers, Clum arrived at the reservation on August 4,1874. During his tenure at San Carlos, he struck a friendship with Eskiminzin, an Aravaipa Apache chief. Clum won the Indians confidence and the Apaches responded by turning in their weapons, the Apaches formed a tribal court to try minor infractions and joined the Tribal Police organized under Clums command, which helped to form a system of limited Indian self-rule. The agent soon attracted 4,200 Apache and Yavapai Indians to the semi-arid reservation, the Army bristled at Clums actions because they prevented them from taking part of the funds that passed through the reservation. On April 21,1877, Clum, along with 100 of his best Apache Police, the U. S. Army, which had mounted intense efforts to track down and capture Geronimo, was seriously embarrassed by Clums success. Indian Bureau administrators and U. S. Army commanders disliked Clums methods, Clum finally resigned, and the reservations new administrators released Geronimo, resulting in more than 15 years of conflict across the American southwest. In March 1875, the government closed the Yavapai-Apache Camp Verde Reservation, more than 100 Yavapai died during the winter trek. After the Chiricahuan Apache were deported east to Florida in 1886, by the early 1900s, Yavapais were drifting away from the San Carlos Reservation and were requesting permission to live at the original Camp Verde Reservation. After the Indian Reorganization Act of 1934, the various Apache groups formed a government, grenville Goodwin, an anthropologist who had lived with the Western Apache since the late 1920s, helped them to decide what government they wanted to form under the new law to gain more sovereignty. The ANCC encourages individuals and corporations to form relationships with Arizonas tribal governments. The San Carlos Apache Tribe Wellness Center, established in 2003, is a tribally run out-patient mental health, the new expanded clinic includes two round group rooms designed to simulate traditional Apache wickiups as well as sky lights to bring natural lighting into interior spaces and outside meeting space. The San Carlos Apache Tribe’s Language Preservation Program, located in Peridot, Arizona, began its outreach in 2011 to the 14,000 tribal members to help preserve, in 2014, tribal Chairman Terry Rambler announced the establishment of the San Carlos Tribal College. The tribe signed an Memorandum of understanding with Arizona State University to help develop curriculum for its proposed two-year Associate degree. The Act cleared the way for the swap in which Resolution Copper would receive 2,422 acres of National Forest land in exchange for deeding to the federal government 5,344 acres of private land
33.
Mount Graham red squirrel
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The Mount Graham red squirrel is an endangered subspecies of the American red squirrel native to the Pinaleño Mountains of Arizona. It is smaller than most other subspecies of red squirrel, and its diet consists mainly of mixed seeds, conifer cones and air-dried fungi. It exhibits similar behavior to other squirrels in its species, the Mount Graham red squirrel is a generally tiny squirrel weighing on average around 8 ounces and measuring about 8 inches in length. The subspecies also has a 6 inches tail, unlike most other squirrels in its species, the squirrels do not have a white-fringed tail. Both females and males share similar markings and features and are grayish brown in color with rusty yellow or orange markings on their backside. During the winter season the squirrels ears are tufted with fur, the skull of the subspecies is rounded and its teeth are low-crowned. Mount Graham red squirrels behave in a similar to most other subspecies of American red squirrel. They are diurnal and do not hibernate during the winter months, Mount Graham squirrels usually eat a diet of mixed seeds, conifer cones and air-dried fungi. Recent data shows that it more frequently at the ecotone zone than the other habitats. When choosing a potential nesting site, the squirrels typically pick a cool, drought, forest fires, and insect infestation have been responsible for a decrease of the squirrel in the spruce-fir habitat. The Mount Graham subspecies was believed to be extinct in the 1950s, after its rediscovery, it was suggested for threatened or endangered species status under the Endangered Species Act in 1982. On May 21,1986, the subspecies was officially recommended to become an endangered species, habitat loss is also occurring at high levels for a variety of natural and anthropogenic reasons. In 1988, the U. S. Fish and Wildlife Service designated most of area as a refuge. USFWS Page Mount Graham Red Squirrel Research Program at School of Natural Resources and the Environment at University of Arizona
34.
United States Congress
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The United States Congress is the bicameral legislature of the federal government of the United States consisting of two chambers, the Senate and the House of Representatives. The Congress meets in the Capitol in Washington, D. C, both senators and representatives are chosen through direct election, though vacancies in the Senate may be filled by a gubernatorial appointment. Members are usually affiliated to the Republican Party or to the Democratic Party, Congress has 535 voting members,435 Representatives and 100 Senators. The House of Representatives has six non-voting members in addition to its 435 voting members and these members can, however, sit on congressional committees and introduce legislation. Puerto Rico, American Samoa, Guam, the Northern Mariana Islands, the members of the House of Representatives serve two-year terms representing the people of a single constituency, known as a district. Congressional districts are apportioned to states by using the United States Census results. Each state, regardless of population or size, has two senators, currently, there are 100 senators representing the 50 states. Each senator is elected at-large in their state for a term, with terms staggered. The House and Senate are equal partners in the legislative process—legislation cannot be enacted without the consent of both chambers, however, the Constitution grants each chamber some unique powers. The Senate ratifies treaties and approves presidential appointments while the House initiates revenue-raising bills, the House initiates impeachment cases, while the Senate decides impeachment cases. A two-thirds vote of the Senate is required before a person can be forcibly removed from office. The term Congress can also refer to a meeting of the legislature. A Congress covers two years, the current one, the 115th Congress, began on January 3,2017, the Congress starts and ends on the third day of January of every odd-numbered year. Members of the Senate are referred to as senators, members of the House of Representatives are referred to as representatives, congressmen, or congresswomen. One analyst argues that it is not a solely reactive institution but has played a role in shaping government policy and is extraordinarily sensitive to public pressure. Several academics described Congress, Congress reflects us in all our strengths, Congress is the governments most representative body. Congress is essentially charged with reconciling our many points of view on the public policy issues of the day. —Smith, Roberts, and Wielen Congress is constantly changing and is constantly in flux, most incumbents seek re-election, and their historical likelihood of winning subsequent elections exceeds 90 percent
35.
NGC 891
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NGC891 is an edge-on unbarred spiral galaxy about 30 million light-years away in the constellation Andromeda. It was discovered by William Herschel on October 6,1784, the galaxy is a member of the NGC1023 group of galaxies in the Local Supercluster. The object is visible in small to moderate size telescopes as a faint elongated smear of light with a dust lane visible in larger apertures, in 1999, the Hubble Space Telescope imaged NGC891 in infrared. In 2005, due to its attractiveness and scientific interest, NGC891 was selected to be the first light image of the Large Binocular Telescope, in 2012, it was again used as a first light image of the Discovery Channel Telescope with the Large Monolithic Imager. Supernova SN 1986J was discovered on August 21,1986 at apparent magnitude 14, despite this, recent high-resolution images of its dusty disk show unusual filamentary patterns. These patterns are extending into the halo of the galaxy, away from its galactic disk, scientists presume that supernova explosions caused this interstellar dust to be thrown out of the galactic disk toward the halo. It may also be possible that the pressure from surrounding stars causes this phenomenon. The galaxy is a member of a group of galaxies, sometimes called the NGC1023 Group. Other galaxies in this group are the NGCs 925,949,959,1003,1023, and 1058, and the UGCs 1807,1865,2014,2023,2034, and 2259. Its outskirts are populated by multiple low-surface brightness, coherent, and vast substructures, the bulge and the disk are surrounded by a flat and thick cocoon-like stellar structure. These have vertical and radial distances of up to 15 kpc and 40 kpc, respectively and are interpreted as the remmant of a satellite galaxy disrupted and in the process of being absorbed by NGC891. The soundtrack of the 1974 film Dark Star by John Carpenter features a muzak style instrumental piece called When Twilight Falls On NGC891, the first solo album by Edgar Froese, Aqua, contained a track called NGC891. Side 2 of the album, which included this track, was unusual in having been an example of a commercially issued piece of music recorded using the artificial head system
36.
Line-of-sight propagation
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Line-of-sight propagation is a characteristic of electromagnetic radiation or acoustic wave propagation which means waves which travel in a direct path from the source to the receiver. Electromagnetic transmission includes light emissions traveling in a straight line, the rays or waves may be diffracted, refracted, reflected, or absorbed by atmosphere and obstructions with material and generally cannot travel over the horizon or behind obstacles. In contrast to line-of-sight propagation, at low frequency due to radio waves can travel as ground waves. This enables AM broadcast radio stations to transmit beyond the horizon, however, at frequencies above 30 MHz and in lower levels of the atmosphere, neither of these effects are significant. Thus, any obstruction between the antenna and the receiving antenna will block the signal, just like the light that the eye may sense. The farthest possible point of propagation is referred to as the radio horizon, in practice, the propagation characteristics of these radio waves vary substantially depending on the exact frequency and the strength of the transmitted signal. Broadcast FM radio, at low frequencies of around 100 MHz, are less affected by the presence of buildings. Low-powered microwave transmitters can be foiled by tree branches, or even heavy rain or snow, if a direct visual fix cannot be taken, it is important to take into account the curvature of the Earth when calculating line-of-sight from maps. Designs for microwave used to use 4/3 earth radius to compute clearances along the path, the presence of objects not in the direct visual line of sight can interfere with radio transmission. This is caused by diffraction effects, for the best propagation, reflected radiation from the ground plane also acts to cancel out the direct signal. This effect, combined with the free-space r−2 propagation loss to a r−4 propagation loss and this effect can be reduced by raising either or both antennas further from the ground, the reduction in loss achieved is known as height gain. Although the frequencies used by mobile phones are in the line-of-sight range, for mobile phone services, these problems are tackled using, rooftop or hilltop positioning of base stations many base stations. A phone can typically see at least three, and usually as many as six at any given time, sectorized antennas at the base stations. Instead of one antenna with omnidirectional coverage, the station may use as few as 3 or as many as 32 separate antennas and this allows the base station to use a directional antenna that is pointing at the user, which improves the signal to noise ratio. If the user moves from one sector to another, the base station automatically selects the proper antenna. Electromagnetic radiation is blocked where the wavelength is longer than any gaps and this means that windowless metal enclosures will completely block cell signs, such as elevator cabins, and parts of trains, cars, and ships. The same problem can affect signals in buildings with steel reinforcement. The radio horizon is the locus of points at which direct rays from an antenna are tangential to the surface of the Earth, if the Earth was a perfect sphere and there was no atmosphere, the radio horizon would be a circle
37.
Aperture synthesis
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The image of the source is produced from these measurements. Astronomical interferometers are used for high-resolution optical, infrared, submillimetre. Aperture synthesis is only if both the amplitude and the phase of the incoming signal are measured by each telescope. Accurate optical delay and atmospheric wavefront aberration correction is required, a demanding technology which became possible only in the 1990s. This is why imaging with aperture synthesis has been used successfully in radio astronomy since the 1950s, see astronomical interferometer for more information. The number of baselines for an array of n telescopes is given by nb=/2, for example the Very Large Array has 27 telescopes giving 351 independent baselines at once, and can give high quality images. In contrast to radio arrays, the largest optical arrays currently have only 6 telescopes, most aperture synthesis interferometers use the rotation of the Earth to increase the number of different baselines included in an observation. The use of Earth rotation was discussed in detail in the 1950 paper A preliminary survey of the stars in the Northern Hemisphere. Some instruments use artificial rotation of the interferometer array instead of Earth rotation, aperture synthesis imaging was first developed at radio wavelengths by Martin Ryle and coworkers from the Radio Astronomy Group at Cambridge University. Martin Ryle and Tony Hewish jointly received a Nobel Prize for this, the radio astronomy group in Cambridge went on to found the Mullard Radio Astronomy Observatory near Cambridge in the 1950s. The technique was further developed in Very Long Baseline Interferometry to obtain baselines of thousands of kilometres. Aperture synthesis is used by a type of radar system known as synthetic aperture radar
38.
Secondary mirror
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A secondary mirror is the second deflecting or focusing mirror element in a reflecting telescope. Light gathered by the mirror is directed towards a focal point typically past the location of the secondary. Secondary mirrors in the form of a flat diagonal mirror are used to re-direct the light path in designs such as Newtonian reflectors. They are also used to re-direct and extend the light path, list of telescope parts and construction Mirror mount Point spread function
39.
Strehl ratio
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The Strehl ratio is a measure of the quality of optical image formation, originally proposed by Karl Strehl, after whom the term is named. Due to diffraction, even a system which is perfect according to geometrical optics will have a limited spatial resolution. In the usual case of a circular aperture, the point spread function which describes the image formed from an object with no spatial extent, is given by the Airy disk as illustrated here. For a circular aperture, the intensity found at the center of the Airy disk defines the point source image intensity required for a Strehl ratio of unity. An imperfect optical system using the physical aperture will generally produce a broader PSF in which the peak intensity is reduced according to the factor given by the Strehl ratio. Typically, as wavelength is increased, an optical system will have a broader PSF with a decreased peak intensity. The ratio is used to assess the quality of astronomical seeing in the presence of atmospheric turbulence. It is also used for the selection of short exposure images in the imaging method. That includes most telescopes and microscopes, but excludes most photographic systems, circle of confusion Fraunhofer diffraction Fraunhofer diffraction Huygens–Fresnel principle Optical transfer function Discussion page R. F
40.
Discovery Channel
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Discovery Channel is an American basic cable and satellite television channel that is the flagship television property of Discovery Communications, a publicly traded company run by CEO David Zaslav. S. Flagship channel and its various owned or licensed television channels internationally, programming on the flagship Discovery Channel in the U. S. A popular annual feature on the channel is Shark Week, which airs on Discovery during the summer months, as of February 2015, Discovery Channel is available to approximately 96,589,000 pay television households in the United States. John Hendricks founded the channel and its parent company, Cable Educational Network Inc. in 1982, several investors raised $5 million in start-up capital to launch the network. The Discovery Channel began broadcasting on June 17,1985 and it was initially available to 156,000 households and broadcast for 12 hours each day between 3 p. m. and 3 a. m. About 75 percent of its content had never been broadcast on U. S. television before. In its early years, the focus centered on educational programming in the form of cultural and wildlife documentaries. It also broadcast some Soviet programming during this time, including the news program Vremya, in 1988, the channel premiered the nightly program World Monitor. By 1990, the channel was available in over 50 million households, the drop in viewership was widely attributed to an over-reliance on a few hit series, such as Monster Garage and American Chopper. Some critics said such shows strayed from Discoverys intention of providing more educationally based shows aimed at helping viewers learn about the world around them, in 2005, Discovery changed its programming focus to include more popular science and historical themes. The networks ratings eventually recovered in 2006, the network was nominated for seven Primetime Emmy Awards that year for shows including The Flight that Fought Back and Deadliest Catch. In 2007, Discovery Channels top series included the Emmy Award- and Peabody Award-winning Planet Earth, Dirty Jobs, MythBusters, Discovery Channels 2008 lineup included Fight Quest and Smash Lab. On September 1,2010, 43-year-old James Jay Lee entered the Discovery Communications headquarters in Silver Spring, Maryland, Lee fired at least one shot and held several employees hostage, he was later shot dead by police. Lee had published criticisms of the network at Savetheplanetprotest. com, in December 2015, Discovery Communications launched its TV Everywhere service, Discovery Go, which features live and video-on-demand content from Discovery Channel and eight of its sister networks. Popular programs on the channel have included the Shark Week programming event, Deadliest Catch, MythBusters, How Its Made, Dirty Jobs, Cash Cab, Christopher Lowell won a Daytime Emmy Award in 2000 for The Christopher Lowell Show. After the 2007 victory with the Spaniard Alberto Contador, Discovery Channel discontinued the cycling sponsorship, Discovery Channel Radio was a radio network, whose programming consisted of audio versions of popular programs from the Discovery Communications family of television channels. Discovery Channel Radio was previously carried by XM Satellite Radio, until its removal from the provider in early September 2005, sirius Satellite Radio dropped Discovery Radio from its lineup on February 21,2007, it was also carried on both of Canadas major satellite radio services. Discovery Channel lent its brand to stores in malls and other locations across America
41.
Television
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Television or TV is a telecommunication medium used for transmitting moving images in monochrome, or in color, and in two or three dimensions and sound. The term can refer to a set, a television program. Television is a medium for entertainment, education, news, politics, gossip. Television became available in experimental forms in the late 1920s. After World War II, a form of black-and-white TV broadcasting became popular in the United States and Britain, and television sets became commonplace in homes, businesses. During the 1950s, television was the medium for influencing public opinion. In the mid-1960s, color broadcasting was introduced in the US, for many reasons, the storage of television and video programming now occurs on the cloud. At the end of the first decade of the 2000s, digital television transmissions greatly increased in popularity, another development was the move from standard-definition television to high-definition television, which provides a resolution that is substantially higher. HDTV may be transmitted in various formats, 1080p, 1080i, in 2013, 79% of the worlds households owned a television set. Most TV sets sold in the 2000s were flat-panel, mainly LEDs, major manufacturers announced the discontinuation of CRT, DLP, plasma, and even fluorescent-backlit LCDs by the mid-2010s. In the near future, LEDs are gradually expected to be replaced by OLEDs, also, major manufacturers have announced that they will increasingly produce smart TVs in the mid-2010s. Smart TVs with integrated Internet and Web 2.0 functions became the dominant form of television by the late 2010s, Television signals were initially distributed only as terrestrial television using high-powered radio-frequency transmitters to broadcast the signal to individual television receivers. Alternatively television signals are distributed by cable or optical fiber, satellite systems and. Until the early 2000s, these were transmitted as analog signals, a standard television set is composed of multiple internal electronic circuits, including a tuner for receiving and decoding broadcast signals. A visual display device which lacks a tuner is correctly called a video monitor rather than a television, the word television comes from Ancient Greek τῆλε, meaning far, and Latin visio, meaning sight. The Anglicised version of the term is first attested in 1907 and it was. formed in English or borrowed from French télévision. In the 19th century and early 20th century, other. proposals for the name of a technology for sending pictures over distance were telephote. The abbreviation TV is from 1948, the use of the term to mean a television set dates from 1941
