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Catalina Real-Time Transient Survey
The Catalina Real-Time Transient Survey is a collaboration using three telescopes looking for optical transients. The same telescopes are used as in the Catalina Sky Survey. They are Mt. Lemmon Survey, Catalina Sky Survey, and Siding Spring Survey. When transients are detected they are alerted on a short time scale so that others can observe the event as well using VOEventNet and SkyAlert. It has detected supernovae, cataclysmic variables, blazars, active galactic nuclei An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a much-higher-than-normal luminosity over at least some portion of the electromagnetic spectrum with characteristics indicating that the luminosity is not prod ... and flares. References Astronomical surveys Observational astronomy {{Astronomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Transient
Time-domain astronomy is the study of how astronomical objects change with time. Though the study may be said to begin with Galileo's ''Letters on Sunspots'', the term now refers especially to variable objects beyond the Solar System. This may be due to movement or changes in the object itself. Common targets included are supernovae, pulsating stars, novas, flare stars, blazars and active galactic nuclei. Visible light time domain studies include OGLE, HAT-South, PanSTARRS, SkyMapper, ASAS, WASP, CRTS, and in a near future the LSST at the Vera C. Rubin Observatory. Time-domain astronomy studies transient astronomical events, often shortened by astronomers to a transients as well as various types of variable stars, including periodic, quasi-periodic, and that of changing behavior or type. Other causes of time variability are asteroids, high proper motion stars, planetary transits and comets. Transients characterize astronomical objects or phenomena whose duration of prese ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catalina Sky Survey
Catalina Sky Survey (CSS; obs. code: 703) is an astronomical survey to discover comets and asteroids. It is conducted at the Steward Observatory's Catalina Station, located near Tucson, Arizona, in the United States. CSS focuses on the search for near-Earth objects, in particular on any potentially hazardous asteroid that may pose a threat of impact. Its counterpart in the southern hemisphere was the Siding Spring Survey (SSS), closed in 2013 due to loss of funding. CSS supersedes the photographic Bigelow Sky Survey. Mission The NEO Observations Program is a result of a United States 1998 congressional directive to NASA to begin a program to identify 1 kilometre (0.62 mile) or larger objects to around 90 percent confidence level or better. The Catalina Sky Survey, located at the Mount Lemmon Observatory in the Catalina Mountains north of Tucson, carries out searches for near-earth objects, NEOs, contributing to the congressionally mandated goal. In addition to identifying ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siding Spring Survey
The Siding Spring Survey (SSS) was a near-Earth object search program that used the 0.5-metre Uppsala Southern Schmidt Telescope at Siding Spring Observatory, New South Wales, Australia. It was the southern hemisphere counterpart of the Catalina Sky Survey (CSS) located in the Santa Catalina Mountains on Mount Bigelow, near Tucson, Arizona, USA. The survey was the only professional search for dangerous asteroids being made in the Southern Hemisphere. SSS was jointly operated by the University of Arizona and the Australian National University, with funding from NASA. SSS (IAU observatory code E12) was located at Siding Spring Observatory (IAU observatory code 413) at , approximately north-west of Sydney at an altitude of about . Images of 30 seconds' exposure time were collected using a 4×4K charge-coupled device at intervals and then compared with software. The survey ended in July 2013 after funding was discontinued. Discoveries Since 2004 the survey has discovere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supernova
A supernova is a powerful and luminous explosion of a star. It has the plural form supernovae or supernovas, and is abbreviated SN or SNe. This transient astronomical event occurs during the last evolutionary stages of a massive star or when a white dwarf is triggered into runaway nuclear fusion. The original object, called the ''progenitor'', either collapses to a neutron star or black hole, or is completely destroyed. The peak optical luminosity of a supernova can be comparable to that of an entire galaxy before fading over several weeks or months. Supernovae are more energetic than novae. In Latin language, Latin, ''nova'' means "new", referring astronomically to what appears to be a temporary new bright star. Adding the prefix "super-" distinguishes supernovae from ordinary novae, which are far less luminous. The word ''supernova'' was coined by Walter Baade and Fritz Zwicky in 1929. The last supernova to be directly observed in the Milky Way was Kepler's Supernova in 160 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cataclysmic Variable
In astronomy, cataclysmic variable stars (CVs) are stars which irregularly increase in brightness by a large factor, then drop back down to a quiescent state. They were initially called novae (), since ones with an outburst brightness visible to the naked eye and an invisible quiescent brightness appeared as new stars in the sky. Cataclysmic variable stars are binary stars that consist of two components; a white dwarf primary, and a mass transferring secondary. The stars are so close to each other that the gravity of the white dwarf distorts the secondary, and the white dwarf accretes matter from the companion. The tightest currently observed orbit in a hydrogen-rich system is 51 minutes in ZTF J1813+4251. Therefore, the secondary is often referred to as the ''donor star''. The infalling matter, which is usually rich in hydrogen, forms in most cases an accretion disk around the white dwarf. Strong UV and X-ray emission is often seen from the accretion disc, powered by the loss ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blazar
A blazar is an active galactic nucleus (AGN) with a relativistic jet (a jet composed of ionized matter traveling at nearly the speed of light) directed very nearly towards an observer. Relativistic beaming of electromagnetic radiation from the jet makes blazars appear much brighter than they would be if the jet were pointed in a direction away from Earth. Blazars are powerful sources of emission across the electromagnetic spectrum and are observed to be sources of high-energy gamma ray photons. Blazars are highly variable sources, often undergoing rapid and dramatic fluctuations in brightness on short timescales (hours to days). Some blazar jets exhibit apparent superluminal motion, another consequence of material in the jet traveling toward the observer at nearly the speed of light. The blazar category includes BL Lac objects and optically violently variable (OVV) quasars. The generally accepted theory is that BL Lac objects are intrinsically low-power radio galaxies while ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Active Galactic Nuclei
An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a much-higher-than-normal luminosity over at least some portion of the electromagnetic spectrum with characteristics indicating that the luminosity is not produced by stars. Such excess non-stellar emission has been observed in the radio, microwave, infrared, optical, ultra-violet, X-ray and gamma ray wavebands. A galaxy hosting an AGN is called an "active galaxy". The non-stellar radiation from an AGN is theorized to result from the accretion of matter by a supermassive black hole at the center of its host galaxy. Active galactic nuclei are the most luminous persistent sources of electromagnetic radiation in the universe, and as such can be used as a means of discovering distant objects; their evolution as a function of cosmic time also puts constraints on models of the cosmos. The observed characteristics of an AGN depend on several properties such as the mass of the central black hole, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flare Star
A flare star is a variable star that can undergo unpredictable dramatic increases in brightness for a few minutes. It is believed that the flares on flare stars are analogous to solar flares in that they are due to the magnetic energy stored in the stars' atmospheres. The brightness increase is across the spectrum, from X-rays to radio waves. The first known flare stars ( V1396 Cygni and AT Microscopii) were discovered in 1924. However, the best-known flare star is UV Ceti, first observed to flare in 1948. Today similar flare stars are classified as UV Ceti type variable stars (using the abbreviation UV) in variable star catalogs such as the General Catalogue of Variable Stars. Most flare stars are dim red dwarfs, although recent research indicates that less massive brown dwarfs might also be capable of flaring. The more massive RS Canum Venaticorum variables (RS CVn) are also known to flare, but it is understood that these flares are induced by a companion star in a binary system ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Surveys
An astronomical survey is a general map or image of a region of the sky (or of the whole sky) that lacks a specific observational target. Alternatively, an astronomical survey may comprise a set of images, spectra, or other observations of objects that share a common type or feature. Surveys are often restricted to one band of the electromagnetic spectrum due to instrumental limitations, although multiwavelength surveys can be made by using multiple detectors, each sensitive to a different bandwidth. Surveys have generally been performed as part of the production of an astronomical catalog. They may also search for transient astronomical events. They often use wide-field astrographs. Scientific value Sky surveys, unlike targeted observation of a specific object, allow astronomers to catalog celestial objects and perform statistical analyses on them without complex corrections for selection effects. In some cases, an astronomer interested in a particular object will find tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
