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Ladd Observatory
Ladd Observatory is an astronomical observatory at Brown University in Providence, Rhode Island. Founded in 1891 it was primarily designed for student instruction and also research. The facility operated a regional timekeeping service. It was responsible for the care and calibration of clocks on campus including one at Carrie Tower and another that rang the class bell at University Hall. Meteorological observations were made there from the time the building opened using recording weather instruments. In addition to general astronomy courses it was also used for teaching civil engineering topics such as geodesy. Nautical science subjects, including celestial navigation, were taught there during the First World War. Ladd began a regular schedule of open nights for public viewing in 1930. This led to the creation of the Skyscrapers amateur astronomy society in 1932 which regularly met at Ladd. The Skyscrapers then acquired the Seagrave Observatory in 1936 which was then used as a m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brown University
Brown University is a private research university in Providence, Rhode Island. Brown is the seventh-oldest institution of higher education in the United States, founded in 1764 as the College in the English Colony of Rhode Island and Providence Plantations. Brown is one of nine colonial colleges chartered before the American Revolution. Admissions at Brown is among the most selective in the United States. In 2022, the university reported a first year acceptance rate of 5%. It is a member of the Ivy League. Brown was the first college in the United States to codify in its charter that admission and instruction of students was to be equal regardless of their religious affiliation. The university is home to the oldest applied mathematics program in the United States, the oldest engineering program in the Ivy League, and the third-oldest medical program in New England. The university was one of the early doctoral-granting U.S. institutions in the late 19th century, adding masters ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Observatory
An observatory is a location used for observing terrestrial, marine, or celestial events. Astronomy, climatology/meteorology, geophysical, oceanography and volcanology are examples of disciplines for which observatories have been constructed. Historically, observatories were as simple as containing an astronomical sextant (for measuring the distance between stars) or Stonehenge (which has some alignments on astronomical phenomena). Astronomical observatories Astronomical observatories are mainly divided into four categories: space-based, airborne, ground-based, and underground-based. Ground-based observatories Ground-based observatories, located on the surface of Earth, are used to make observations in the radio and visible light portions of the electromagnetic spectrum. Most optical telescopes are housed within a dome or similar structure, to protect the delicate instruments from the elements. Telescope domes have a slit or other opening in the roof that can be opened du ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Filar Micrometer
A filar micrometer is a specialized eyepiece used in astronomical telescopes for astrometry measurements, in microscopes for specimen measurements, and in alignment and surveying telescopes for measuring angles and distances on nearby objects. The word ''filar'' derives . It refers to the fine threads or wires used in the device. Construction and use A typical filar micrometer consists of a reticle that has two fine parallel wires or threads that can be moved by the observer using a micrometer screw mechanism. The wires are placed in the focal image plane of the eyepiece so they remain sharply superimposed over the object under observation, while the micrometer motion moves the wires across the focal plane. Other designs employ a fixed reticle, against which one wire or a second reticle moves. By rotating the eyepiece assembly in the eyetube, the measurement axis can be aligned to match the orientation of the two points of observation. At one time, it was common to use s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Occultation
An occultation is an event that occurs when one object is hidden from the observer by another object that passes between them. The term is often used in astronomy, but can also refer to any situation in which an object in the foreground blocks from view (occults) an object in the background. In this general sense, occultation applies to the visual scene observed from low-flying aircraft (or computer-generated imagery) when foreground objects obscure distant objects dynamically, as the scene changes over time. If the closer body does not entirely conceal the farther one, the event is called a '' transit''. Both transit and occultation may be referred to generally as ''occlusion''; and if a shadow is cast onto the observer, it is called an eclipse. The symbol for an occultation, and especially a solar eclipse, is file:Occultation symbol.svg (U+1F775 🝵). Occultations by the Moon The term occultation is most frequently used to describe lunar occultations, those relativ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
George N
George may refer to: People * George (given name) * George (surname) * George (singer), American-Canadian singer George Nozuka, known by the mononym George * George Washington, First President of the United States * George W. Bush, 43rd President of the United States * George H. W. Bush, 41st President of the United States * George V, King of Great Britain, Ireland, the British Dominions and Emperor of India from 1910-1936 * George VI, King of Great Britain, Ireland, the British Dominions and Emperor of India from 1936-1952 * Prince George of Wales * George Papagheorghe also known as Jorge / GEØRGE * George, stage name of Giorgio Moroder * George Harrison, an English musician and singer-songwriter Places South Africa * George, Western Cape ** George Airport United States * George, Iowa * George, Missouri * George, Washington * George County, Mississippi * George Air Force Base, a former U.S. Air Force base located in California Characters * George (Peppa Pig), a 2-year-ol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clock Drive
In astronomy, a clock drive (also known as a field rotator) is a motor-controlled mechanism used to move an equatorial mounted telescope along one axis to keep the aim in exact sync with the apparent motion of the fixed stars on the celestial sphere. Overview Clock drives work by rotating a telescope mount's polar axis, the axis parallel to the Earth's polar axis (also called the right ascension axis) in the opposite direction to the Earth's rotation one revolution every 23 hours and 56 minutes (called ''sidereal day''), thereby canceling that motion. This allows the telescope to stay fixed on a certain point in the sky without having to be constantly re-aimed due to the Earth's rotation. The mechanism itself used to be clockwork but nowadays is usually electrically driven. Clock drives can be light and portable for smaller telescopes or can be exceedingly heavy and complex for larger ones such as the 60-inch telescope at the Mount Wilson Observatory. Clock-driven equatorial p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Equatorial Mount
An equatorial mount is a mount for instruments that compensates for Earth's rotation by having one rotational axis, the polar axis, parallel to the Earth's axis of rotation. This type of mount is used for astronomical telescopes and cameras. The advantage of an equatorial mount lies in its ability to allow the instrument attached to it to stay fixed on any celestial object with diurnal motion by driving one axis at a constant speed. Such an arrangement is called a sidereal or clock drive. Equatorial mounts achieve this by aligning their rotational axis with the Earth, a process known as polar alignment. Astronomical telescope mounts In astronomical telescope mounts, the equatorial axis (the ''right ascension'') is paired with a second perpendicular axis of motion (known as the ''declination''). The equatorial axis of the mount is often equipped with a motorized "''clock drive''", that rotates that axis one revolution every 23 hours and 56 minutes in exact sync with the apparen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jena Glass
Jena glass (German: ''Jenaer Glas'') is a shock- and heat-resistant glass used in scientific and technological applications, especially in chemistry. The glass was invented by Otto Schott in 1884 in Jena, Germany, where he had established Schott AG with Ernst Abbe and Carl Zeiss.Jena glass at Britannica.com Jena glass is a which, in early manufacture, contained added , , |
Flint Glass
Flint glass is optical glass that has relatively high refractive index and low Abbe number (high dispersion). Flint glasses are arbitrarily defined as having an Abbe number of 50 to 55 or less. The currently known flint glasses have refractive indices ranging between 1.45 and 2.00. A concave lens of flint glass is commonly combined with a convex lens of crown glass to produce an achromatic doublet lens because of their compensating optical properties, which reduces chromatic aberration (colour defects). With respect to glass, the term ''flint'' derives from the flint nodules found in the chalk deposits of southeast England that were used as a source of high purity silica by George Ravenscroft, c. 1662, to produce a potash lead glass that was the precursor to English lead crystal. Traditionally, flint glasses were lead glasses containing around 4–60% lead(II) oxide; however, the manufacture and disposal of these glasses were sources of pollution Pollution is the i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crown Glass (optics)
Crown glass is a type of optical glass used in lenses and other optical components. It has relatively low refractive index (≈1.52) and low dispersion (with Abbe numbers around 60). Crown glass is produced from alkali-lime silicates containing approximately 10% potassium oxide and is one of the earliest low dispersion glasses. As well as the specific material named ''crown glass'', there are other optical glasses with similar properties that are also called crown glasses. Generally, this is any glass with Abbe numbers in the range 50 to 85. For example, the borosilicate glass Schott BK7 (Schott designates it as 517642. The first three digits tell you its refractive index (1.517) and the last three tell you its Abbé number (64.2))The crown/flint distinction is so important to optical glass technology that many glass names, notably Schott glasses, incorporate it. A ''K'' in a Schott name indicates a crown glass (''Krone'' in German — Schott is a German company). The ''B'' in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles S
Charles is a masculine given name predominantly found in English and French speaking countries. It is from the French form ''Charles'' of the Proto-Germanic name (in runic alphabet) or ''*karilaz'' (in Latin alphabet), whose meaning was "free man". The Old English descendant of this word was '' Ċearl'' or ''Ċeorl'', as the name of King Cearl of Mercia, that disappeared after the Norman conquest of England. The name was notably borne by Charlemagne (Charles the Great), and was at the time Latinized as ''Karolus'' (as in '' Vita Karoli Magni''), later also as '' Carolus''. Some Germanic languages, for example Dutch and German, have retained the word in two separate senses. In the particular case of Dutch, ''Karel'' refers to the given name, whereas the noun ''kerel'' means "a bloke, fellow, man". Etymology The name's etymology is a Common Germanic noun ''*karilaz'' meaning "free man", which survives in English as churl (< Old English ''ċeorl''), which developed its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Brashear
John Alfred Brashear (November 24, 1840 – April 8, 1920) was an American astronomer and instrument builder. Life and work Brashear was born in Brownsville, Pennsylvania, a town 35 miles (56 km) south of Pittsburgh along the Monongahela River. His father, Basil Brown Brashear, was a saddler, and his mother, Julia Smith Brashear, was a school teacher. He was the oldest of seven children. As a boy, John Brashear was heavily influenced by his maternal grandfather, Nathanial Smith, a clock repairer. When he was nine, his grandfather took him to view through the telescope of 'Squire' Joseph P. Wampler, who set up his traveling telescope in Brownsville. That influential view of the moon and the planet Saturn stayed with Brashear for the rest of his life. After receiving a common school education until age 15, he became an apprentice to a machinist and had mastered his trade at age 20. Beginning in 1861 Brashear worked as a millwright in a rolling steel mill in Pittsburgh. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
