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Transit Instrument
In astronomy, a transit instrument is a small telescope with extremely precisely graduated mount used for the precise observation of star positions. They were previously widely used in astronomical observatories and naval observatories to measure star positions in order to compile nautical almanacs for use by mariners for celestial navigation, and observe star transits to set extremely accurate clocks ( astronomical regulators) which were used to set marine chronometers carried on ships to determine longitude, and as primary time standards before atomic clocks. The instruments can be divided into three groups: meridian, zenith, and universal instruments. Types Meridian instruments For observation of star transits in the exact direction of South or North: * Meridian circles, Mural quadrants etc. * Passage instruments (transportable, also for prime vertical transits) Zenith instruments * Zenith telescope * Photozenith tube (PZT) * zenith cameras * Danjon astrolabe, Zei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meridian Circle - Kuffner Observatory
Meridian or a meridian line (from Latin ''meridies'' via Old French ''meridiane'', meaning “midday”) may refer to Science * Meridian (astronomy), imaginary circle in a plane perpendicular to the planes of the celestial equator and horizon **Central meridian (planets) * Meridian (geography), an imaginary arc on the Earth's surface from the North Pole to the South Pole ** Meridian arc, the distance between two points with the same longitude ** Prime meridian, origin of longitudes ** Principal meridian, arbitrary meridians used as references in land surveying * Meridian line, used with a gnomon to Sundial#Meridian lines, measure solar elevation and time of year * Autonomous sensory meridian response, a static-like or tingling sensation on the skin Places Cities and towns * Meridian, California (other), U.S., multiple California towns named Meridian * Meridian, Colorado, U.S. * Meridian, Florida, U.S. * Meridian, Georgia, U.S. * Meridian, Idaho, U.S. * Meridian, Mississ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Transit
In astronomy, a transit (or astronomical transit) is a phenomenon when a celestial body passes directly between a larger body and the observer. As viewed from a particular vantage point, the transiting body appears to move across the face of the larger body, covering a small portion of it. The word "transit" refers to cases where the nearer object appears smaller than the more distant object. Cases where the nearer object appears larger and completely hides the more distant object are known as ''occultations''. However, the probability of seeing a transiting planet is low because it is dependent on the alignment of the three objects in a nearly perfectly straight line. Many parameters of a planet and its parent star can be determined based on the transit. In the Solar System One example of a transit involves the motion of a planet between a terrestrial observer and the Sun. This can happen only with inferior planets, namely Mercury and Venus (see transit of Mercury and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tycho Brahe
Tycho Brahe ( ; born Tyge Ottesen Brahe; generally called Tycho (14 December 154624 October 1601) was a Danish astronomer, known for his comprehensive astronomical observations, generally considered to be the most accurate of his time. He was known during his lifetime as an astronomer, astrologer, and alchemist. He was the last major astronomer before the invention of the telescope. An heir to several noble families, Tycho was well-educated. He took an interest in astronomy and in the creation of more accurate instruments of measurement. He worked to combine what he saw as the geometrical benefits of Copernican heliocentrism with the philosophical benefits of the Ptolemaic system, and devised the Tychonic system, his own version of a model of the universe, with the Sun orbiting the Earth, and the planets as orbiting the Sun. In ''De nova stella'' (1573), he refuted the Aristotelian belief in an unchanging celestial realm. His measurements indicated that "new stars" (''stellae ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electro Optic
Electro–optics is a branch of electrical engineering, electronic engineering, materials science, and material physics involving components, electronic devices such as lasers, laser diodes, LEDs, waveguides, etc. which operate by the propagation and interaction of light with various tailored materials. It is closely related to the branch of optics, involving application of generation of photons, called photonics. It is not only concerned with the "electro–optic effect", since it deals with the interaction between the electromagnetic (optical) and the electrical (electronic) states of materials. Electro-optical devices The electro-optic effect is a change in the optical properties of an optically active material due to interaction with light. This interaction usually results in a change in the birefringence, and not simply the refractive index of the medium. In a Kerr cell, the change in birefringence is proportional to the square of the optical electric field, and the mat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charge-coupled Device
A charge-coupled device (CCD) is an integrated circuit containing an array of linked, or coupled, capacitors. Under the control of an external circuit, each capacitor can transfer its electric charge to a neighboring capacitor. CCD sensors are a major technology used in digital imaging. In a CCD image sensor, pixels are represented by p-doped metal–oxide–semiconductor (MOS) capacitors. These MOS capacitors, the basic building blocks of a CCD, are biased above the threshold for inversion when image acquisition begins, allowing the conversion of incoming photons into electron charges at the semiconductor-oxide interface; the CCD is then used to read out these charges. Although CCDs are not the only technology to allow for light detection, CCD image sensors are widely used in professional, medical, and scientific applications where high-quality image data are required. In applications with less exacting quality demands, such as consumer and professional digital cameras, act ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Impersonal Micrometer , a verb that cannot take a true subject
{{Disambig ...
Impersonality may refer to: * Impersonal passive voice, a verb voice that decreases the valency of an intransitive verb to zero * Impersonal verb In linguistics, an impersonal verb is one that has no determinate subject. For example, in the sentence "''It rains''", ''rain'' is an impersonal verb and the pronoun ''it'' does not refer to anything. In many languages the verb takes a third per ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chronograph
A chronograph is a specific type of watch that is used as a stopwatch combined with a display watch. A basic chronograph has an independent sweep second hand and a minute sub-dial; it can be started, stopped, and returned to zero by successive pressure on the stem. More complex chronographs use additional Complication (horology), complications and can have multiple sub-dials to measure seconds, minutes, hours and even fractions of a second. In addition, many modern chronographs use moveable bezels as Tachymeter (watch), tachymeters for rapid calculations of speed or distance. Louis Moinet invented the chronograph in 1816 for use in tracking astronomical objects. Chronographs were also used heavily in artillery fire in the mid to late 1800s. More modern uses of chronographs involve aircraft piloting, auto racing, Underwater diving, diving and submarine maneuvering. Since the 1980s, the term ''chronograph'' has also been applied to all Watch#Digital, digital watches that incorpor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stopwatch
A stopwatch is a timepiece designed to measure the amount of time that elapses between its activation and deactivation. A large digital version of a stopwatch designed for viewing at a distance, as in a sports stadium, is called a stop clock. In manual timing, the clock is started and stopped by a person pressing a button. In fully automatic time, both starting and stopping are triggered automatically, by sensors. The timing functions are traditionally controlled by two buttons on the case. Pressing the top button starts the timer running, and pressing the button a second time stops it, leaving the elapsed time displayed. A press of the second button then resets the stopwatch to zero. The second button is also used to record ''split times'' or ''lap times''. When the split time button is pressed while the watch is running it allows the elapsed time to that point to be read, but the watch mechanism continues running to record total elapsed time. Pressing the split button a s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cinetheodolite
A cinetheodolite (a.k.a. ''kinetheodolite'') is a photographic instrument for collection of trajectory data. It can be used to acquire data in the testing of missiles, rockets, projectiles, aircraft, and fire control systems; in the ripple firing of rockets, graze action tests, air burst fuze tests, and similar operations. Cinetheodolites provide angular measurements of the line of sight to the vehicle. This permits acquiring accurate position data. Together with timing systems, velocity and acceleration data can be developed from the position measurements. Cinetheodolites can serve as primary sources of position and velocity data to about 30 km slant range. These instruments were developed from theodolites by the addition of a movie camera, adding the ability to track a vehicle in flight and so obtain continuous trajectory data. Introduction One of the objectives of testing missile and rocket systems is to determine the actual "in-flight" performance of the vehicles themse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theodolite
A theodolite () is a precision optical instrument for measuring angles between designated visible points in the horizontal and vertical planes. The traditional use has been for land surveying, but it is also used extensively for building and infrastructure construction, and some specialized applications such as meteorology and rocket launching. It consists of a moveable telescope mounted so it can rotate around horizontal and vertical axes and provide angular readouts. These indicate the orientation of the telescope, and are used to relate the first point sighted through the telescope to subsequent sightings of other points from the same theodolite position. These angles can be measured with accuracies down to microradians or seconds of arc. From these readings a plan can be drawn, or objects can be positioned in accordance with an existing plan. The modern theodolite has evolved into what is known as a total station where angles and distances are measured electronically, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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