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Shift-and-add
Speckle imaging describes a range of high-resolution astronomical imaging techniques based on the analysis of large numbers of short exposures that freeze the variation of atmospheric turbulence. They can be divided into the shift-and-add ("''image stacking''") method and the speckle interferometry methods. These techniques can dramatically increase the resolution of ground-based telescopes, but are limited to bright targets. Explanation The principle of all the techniques is to take very short exposure images of astronomical targets, and then process those so as to remove the effects of astronomical seeing. Use of these techniques led to a number of discoveries, including thousands of binary stars that would otherwise appear as a single star to a visual observer working with a similar-sized telescope, and the first images of sunspot-like phenomena on other stars. Many of the techniques remain in wide use today, notably when imaging relatively bright targets. The resolutio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shift-and-add
Speckle imaging describes a range of high-resolution astronomical imaging techniques based on the analysis of large numbers of short exposures that freeze the variation of atmospheric turbulence. They can be divided into the shift-and-add ("''image stacking''") method and the speckle interferometry methods. These techniques can dramatically increase the resolution of ground-based telescopes, but are limited to bright targets. Explanation The principle of all the techniques is to take very short exposure images of astronomical targets, and then process those so as to remove the effects of astronomical seeing. Use of these techniques led to a number of discoveries, including thousands of binary stars that would otherwise appear as a single star to a visual observer working with a similar-sized telescope, and the first images of sunspot-like phenomena on other stars. Many of the techniques remain in wide use today, notably when imaging relatively bright targets. The resolutio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lucky Imaging
Lucky imaging (also called lucky exposures) is one form of speckle imaging used for astrophotography. Speckle imaging techniques use a high-speed camera with exposure times short enough (100 ms or less) so that the changes in the Earth's atmosphere during the exposure are minimal. With lucky imaging, those optimum exposures least affected by the atmosphere (typically around 10%) are chosen and combined into a single image by shifting and adding the short exposures, yielding much higher angular resolution than would be possible with a single, longer exposure, which includes all the frames. Explanation Images taken with ground-based telescopes are subject to the blurring effect of atmospheric turbulence (seen to the eye as the stars twinkling). Many astronomical imaging programs require higher resolution than is possible without some correction of the images. Lucky imaging is one of several methods used to remove atmospheric blurring. Used at a 1% selection or less, luc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zeta Bootis Short Exposure
Zeta (, ; uppercase Ζ, lowercase ζ; grc, ζῆτα, el, ζήτα, label= Demotic Greek, classical or ''zē̂ta''; ''zíta'') is the sixth letter of the Greek alphabet. In the system of Greek numerals, it has a value of 7. It was derived from the Phoenician letter zayin . Letters that arose from zeta include the Roman Z and Cyrillic З. Name Unlike the other Greek letters, this letter did not take its name from the Phoenician letter from which it was derived; it was given a new name on the pattern of beta, eta and theta. The word ''zeta'' is the ancestor of ''zed'', the name of the Latin letter Z in Commonwealth English. Swedish and many Romanic languages (such as Italian and Spanish) do not distinguish between the Greek and Roman forms of the letter; "''zeta''" is used to refer to the Roman letter Z as well as the Greek letter. Uses Letter The letter ζ represents the voiced alveolar fricative in Modern Greek. The sound represented by zeta in Greek before ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of The Optical Society Of America
The ''Journal of the Optical Society of America'' is a peer-reviewed scientific journal of optics, published by Optica. It was established in 1917 and in 1984 was split into two parts, A and B. ''Journal of the Optical Society of America A'' Part A covers various topics in optics, vision, and image science. The editor-in-chief is Olga Korotkova (University of Miami, USA). ''Journal of the Optical Society of America B'' Part B covers various topics in the field of optical physics, such as guided waves, laser spectroscopy, nonlinear optics, quantum optics, lasers, organic and polymer materials for optics, and ultrafast phenomena In optics, an ultrashort pulse, also known as an ultrafast event, is an electromagnetic pulse whose time duration is of the order of a picosecond (10−12 second) or less. Such pulses have a broadband optical spectrum, and can be created by m .... The editor-in-chief is Kurt Busch ( Humboldt University of Berlin, Germany). References {{refli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centroid
In mathematics and physics, the centroid, also known as geometric center or center of figure, of a plane figure or solid figure is the arithmetic mean position of all the points in the surface of the figure. The same definition extends to any object in ''n''-dimensional Euclidean space. In geometry, one often assumes uniform mass density, in which case the '' barycenter'' or ''center of mass'' coincides with the centroid. Informally, it can be understood as the point at which a cutout of the shape (with uniformly distributed mass) could be perfectly balanced on the tip of a pin. In physics, if variations in gravity are considered, then a ''center of gravity'' can be defined as the weighted mean of all points weighted by their specific weight. In geography, the centroid of a radial projection of a region of the Earth's surface to sea level is the region's geographical center. History The term "centroid" is of recent coinage (1814). It is used as a substitute for the old ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IRIS (astronomical Software)
Astrophotography, also known as astronomical imaging, is the photography or imaging of astronomical objects, celestial events, or areas of the night sky. The first photograph of an astronomical object (the Moon) was taken in 1840, but it was not until the late 19th century that advances in technology allowed for detailed stellar photography. Besides being able to record the details of extended objects such as the Moon, Sun, and planets, modern astrophotography has the ability to image objects invisible to the human eye such as dim stars, nebulae, and galaxies. This is done by long time exposure since both film and digital cameras can accumulate and sum photons over these long periods of time. Photography using extended exposure-times revolutionized the field of professional astronomical research, recording hundreds of thousands of new stars, and nebulae invisible to the human eye. Specialized and ever-larger optical telescopes were constructed as essentially big cameras to reco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hugin (software)
Hugin () is a cross-platform open source panorama photo stitching and HDR merging program developed by Pablo d'Angelo and others. It is a GUI front-end for Helmut Dersch's Panorama Tools and Andrew Mihal's '' Enblend'' and ''Enfuse''. Stitching is accomplished by using several overlapping photos taken from the same location, and using control points to align and transform the photos so that they can be blended together to form a larger image. Hugin allows for the easy (optionally automatic) creation of control points between two images, optimization of the image transforms along with a preview window so the user can see whether the panorama is acceptable. Once the preview is correct, the panorama can be fully stitched, transformed and saved in a standard image format. Features Hugin and the associated tools can be used to * combine overlapping images for panoramic photography * correct complete panorama images, e.g. those that are "wavy" due to a badly levelled panoramic camer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Registax
RegiStax is image processing software for amateur astrophotographers, released as freeware, designed to run under Windows, but which also runs on Linux, under wine. Its purpose is to produce enhanced images of astronomic observations through combining consecutive photographs (an image "stack") of the same scene that were taken over a short period of time. The process relies on the subject (e.g. a planet) being unchanged between photographs, so that any differences can be assumed to be random noise or atmospheric interference. The stack of images can be in the form of individual consecutive shots or from frames of a movie camera trained on the scene. History Cor Berrevoets (Netherlands) began development of the program about 2001, and it was released on 19 May 2002. This initial release (version v1.0.0) had facilities for stack alignment, grading and selection of the images to be merged, and image enhancement using techniques such as wavelet processing. The program wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IRAF
IRAF (Image Reduction and Analysis Facility) is a collection of software written at the National Optical Astronomy Observatory (NOAO) geared towards the reduction of astronomical images and spectra in pixel array form. This is primarily data taken from imaging array detectors such as CCDs. It is available for all major operating systems for mainframes and desktop computers. IRAF was designed cross-platform, supporting VMS and UNIX-like operating systems. Use on Microsoft Windows was made possible by Cygwin in earlier versions, and can be today done with the Windows Subsystem for Linux. Today, it is primarily used on macOS and Linux. IRAF commands (known as tasks) are organized into package structures. Additional packages may be added to IRAF. Packages may contain other packages. There are many packages available by NOAO and external developers often focusing on a particular branch of research or facility. Functionality available in IRAF includes the calibration of the fluxes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Image Stabilisation
Image stabilization (IS) is a family of techniques that reduce blurring associated with the motion of a camera or other imaging device during exposure. Generally, it compensates for pan and tilt (angular movement, equivalent to yaw and pitch) of the imaging device, though electronic image stabilization can also compensate for rotation. It is mainly used in high-end image-stabilized binoculars, still and video cameras, astronomical telescopes, and also smartphones. With still cameras, camera shake is a particular problem at slow shutter speeds or with long focal length lenses (telephoto or zoom). With video cameras, camera shake causes visible frame-to-frame jitter in the recorded video. In astronomy, the problem of lens shake is added to variation in the atmosphere, which changes the apparent positions of objects over time. Application in still photography In photography, image stabilization can facilitate shutter speeds 2 to 5.5 stops slower (exposures 4 to times ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gemini North Infrared View Of Jupiter
Gemini may refer to: Space * Gemini (constellation), one of the constellations of the zodiac ** Gemini in Chinese astronomy * Project Gemini, the second U.S. crewed spaceflight program * Gemini Observatory, consisting of telescopes in the Northern and Southern Hemispheres * Gemini Planet Imager, an instrument for observing extrasolar planets Mythology * Gemini (astrology), an astrological sign * Gemini twins, in Greek mythology Arts and entertainment Comics and literature * Gemini (DC Comics), a fictional supervillain * Gemini (Marvel Comics), a fictional character * ''Gemini'', a comic series created by Jay Faerber * Gemini Kanon, a fictional character in the manga ''Saint Seiya'' by Masami Kurumada * Gemini Saga, a fictional character in the manga ''Saint Seiya'' by Masami Kurumada * ''Gemini'' (magazine), a Norwegian periodical * Gemini Publications, an American magazine publisher * ''Gemini'', a 2000 novel by Dorothy Dunnett * ''Gemini'' (''Les Météores''), a 1975 novel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The first laser was built in 1960 by Theodore H. Maiman at Hughes Research Laboratories, based on theoretical work by Charles Hard Townes and Arthur Leonard Schawlow. A laser differs from other sources of light in that it emits light which is ''coherent''. Spatial coherence allows a laser to be focused to a tight spot, enabling applications such as laser cutting and lithography. Spatial coherence also allows a laser beam to stay narrow over great distances (collimation), enabling applications such as laser pointers and lidar (light detection and ranging). Lasers can also have high temporal coherence, which allows them to emit light with a very narrow spectrum. Alternatively, temporal coherence can be used to produce ultrashort pulses ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
