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Gamma-ray Burst Coordinates Network
The gamma-ray burst coordinates network (GCN) is a system that distributes information about the location of a gamma-ray burst (GRB), called ''notices'', when a burst is detected by various spacecraft. The GCN also automatically receives and distributes messages, called ''circulars'', about follow-up observations to interested individuals and institutions. Follow-up observations may be made by ground-based and space-based optical, radio, and X-ray observatories. GCN has its origins in the BATSE coordinates distribution network (BACODINE). The Burst And Transient Source Experiment ( BATSE) was a scientific instrument on the ''Compton Gamma-Ray Observatory'' (CGRO), and BACODINE monitored the BATSE real-time telemetry from CGRO. The first function of BACODINE was calculating the right ascension (RA) and declination (dec) locations for GRBs that it detected, and distributing those locations to sites around the world in real-time. Since the de-orbiting of the CGRO, this function of BA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma-ray Burst
In gamma-ray astronomy, gamma-ray bursts (GRBs) are immensely energetic explosions that have been observed in distant galaxies. They are the most energetic and luminous electromagnetic events since the Big Bang. Bursts can last from ten milliseconds to several hours. After an initial flash of gamma rays, a longer-lived "afterglow" is usually emitted at longer wavelengths (X-ray, ultraviolet, optical, infrared, microwave and radio). The intense radiation of most observed GRBs is thought to be released during a supernova or superluminous supernova as a high-mass star implodes to form a neutron star or a black hole. A subclass of GRBs appear to originate from the merger of binary neutron stars. The sources of most GRBs are billions of light years away from Earth, implying that the explosions are both extremely energetic (a typical burst releases as much energy in a few seconds as the Sun will in its entire 10-billion-year lifetime) and extremely rare (a few per galaxy per milli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
InterPlanetary Network
The InterPlanetary Network (IPN) is a group of spacecraft equipped with gamma ray burst (GRB) detectors. By timing the arrival of a burst at several spacecraft, its precise location can be found. The precision for determining the direction of a GRB in the sky is improved by increasing the spacing of the detectors, and also by more accurate timing of the reception. Typical spacecraft baselines of about one AU (astronomical unit) and time resolutions of tens of milliseconds can determine a burst location within several arcminutes, allowing follow-up observations with other telescopes. Rationale Gamma rays are too energetic to be focused with mirrors. The rays penetrate mirror materials instead of reflecting. Because gamma rays cannot be focused into an image in the traditional sense, a unique location for a gamma ray source cannot be determined as it is done with less energetic light. In addition, gamma ray bursts are brief flashes (often as little as 0.2 seconds) that occur rando ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma-ray Telescopes
A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically shorter than those of X-rays. With frequencies above 30 exahertz (), it imparts the highest photon energy. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation ''gamma rays'' based on their relatively strong penetration of matter; in 1900 he had already named two less penetrating types of decay radiation (discovered by Henri Becquerel) alpha rays and beta rays in ascending order of penetrating power. Gamma rays from radioactive decay are in the energy range from a few kiloelectronvolts (keV) to approximately 8 megaelectronvolts (MeV), corresponding to the typical energy levels in nuclei with reasonably long lifet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma-ray Large Area Space Telescope
The Fermi Gamma-ray Space Telescope (FGST, also FGRST), formerly called the Gamma-ray Large Area Space Telescope (GLAST), is a space observatory being used to perform gamma-ray astronomy observations from low Earth orbit. Its main instrument is the Large Area Telescope (LAT), with which astronomers mostly intend to perform an all-sky survey studying astrophysics, astrophysical and physical cosmology, cosmological phenomena such as active galactic nuclei, pulsars, other high-energy sources and dark matter. Another instrument aboard Fermi, the Gamma-ray Burst Monitor (GBM; formerly GLAST Burst Monitor), is being used to study gamma-ray bursts and solar flares. Fermi, named for high-energy physics pioneer Enrico Fermi, was launched on 11 June 2008 at 16:05 UTC aboard a Delta II 7920-H rocket. The mission is a joint venture of NASA, the United States Department of Energy, and government agencies in France, Germany, Italy, Japan, and Sweden, becoming the most sensitive gamma-ray ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AGILE (spacecraft)
AGILE (Astro‐Rivelatore Gamma a Immagini Leggero) is an X-ray and gamma ray astronomical satellite of the Italian Space Agency (ASI). Objectives AGILE's mission is to observe gamma-ray sources in the universe. AGILE (Astro rivelatore Gamma a Immagini Leggero) is an Italian high-energy astrophysics mission dedicated to the observation of the gamma-ray Universe. Its very innovative instrumentation is unprecedentedly light (100 kg) and the most compact ever operational for high-energy astrophysics (approximately a cube of about 60 cm size) with excellent detection and imaging capability. Satellite data are collected by the ASI ground station in Malindi (Kenya), then quickly transferred to the Satellite Operations Centre in Fucino, transferred, preprocessed, and stored and analyzed at the ASI Science Data Center (ASDC) in Frascati. In parallel the pre-processed data are transferred at INAF/OAS Bologna for a fast science alert generation, thus assuring a very rapid respon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UV Astronomy
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight, and constitutes about 10% of the total electromagnetic radiation output from the Sun. It is also produced by electric arcs and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights. Although long-wavelength ultraviolet is not considered an ionizing radiation because its photons lack the energy to ionize atoms, it can cause chemical reactions and causes many substances to glow or fluoresce. Consequently, the chemical and biological effects of UV are greater than simple heating effects, and many practical applications of UV radiation derive from its interactions with organic molecules. Short-wave ultraviolet light damages DNA and sterilizes surfaces with which it comes into contact. For huma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NEAR Shoemaker
''Near Earth Asteroid Rendezvous – Shoemaker'' (''NEAR Shoemaker''), renamed after its 1996 launch in honor of planetary scientist Eugene Shoemaker, was a robotic space probe designed by the Johns Hopkins University Applied Physics Laboratory for NASA to study the near-Earth asteroid Eros from close orbit over a period of a year. It was the first spacecraft to successfully orbit an asteroid and also land on an asteroid. In February 2000, the mission succeeded in closing in with the asteroid and afterwards orbited it several times. On February 12, 2001, the mission succeeded in touching down on the asteroid. It was terminated just over two weeks later. The primary scientific objective of ''NEAR'' was to return data on the bulk properties, composition, mineralogy, morphology, internal mass distribution and magnetic field of Eros. Secondary objectives include studies of regolith properties, interactions with the solar wind, possible current activity as indicated by dust or gas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BeppoSAX
BeppoSAX was an Italian–Dutch satellite for X-ray astronomy which played a crucial role in resolving the origin of gamma-ray bursts (GRBs), the most energetic events known in the universe. It was the first X-ray mission capable of simultaneously observing targets over more than 3 decades of energy, from 0.1 to 300 kiloelectronvolts (keV) with relatively large area, good (for the time) energy resolution and imaging capabilities (with a spatial resolution of 1 arc minute between 0.1 and 10 keV). BeppoSAX was a major programme of the Italian Space Agency (ASI) with the participation of the Netherlands Agency for Aerospace Programmes (NIVR). The prime contractor for the space segment was Alenia while Nuova Telespazio led the development of the ground segment. Most of the scientific instruments were developed by the Italian National Research Council (CNR) while the Wide Field Cameras were developed by the Netherlands Institute for Space Research (SRON) and the LECS was developed by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Array Of Low Energy X-ray Imaging Sensors
The Array of Low Energy X-ray Imaging Sensors (ALEXIS, also known as P89-1B, COSPAR 1993-026A, SATCAT 22638) X-ray telescope featured curved mirrors whose multilayer coatings reflected and focused low-energy X-rays or extreme ultraviolet (EUV) light the way optical telescopes focus visible light. The satellite and payloads were funded by the United States Department of Energy and built by Los Alamos National Laboratory (LANL) in collaboration with Sandia National Laboratories and the University of California-Space Sciences Lab. The satellite bus was built by AeroAstro, Inc. of Herndon, VA. The Launch was provided by the United States Air Force Space Test Program on a Pegasus Booster on April 25, 1993. The mission was entirely controlled from a small groundstation at LANL. Features ALEXIS scanned half the sky with its three paired sets of EUV telescopes, although it could not locate any events with high resolution. Ground-based optical astronomers could look for visual counterparts ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lightcurve
In astronomy, a light curve is a graph of light intensity of a celestial object or region as a function of time, typically with the magnitude of light received on the y axis and with time on the x axis. The light is usually in a particular frequency interval or band. Light curves can be periodic, as in the case of eclipsing binaries, Cepheid variables, other periodic variables, and transiting extrasolar planets, or aperiodic, like the light curve of a nova, a cataclysmic variable star, a supernova or a microlensing event or binary as observed during occultation events. The study of the light curve, together with other observations, can yield considerable information about the physical process that produces it or constrain the physical theories about it. Variable stars Graphs of the apparent magnitude of a variable star over time are commonly used to visualise and analyse their behaviour. Although the categorisation of variable star types is increasingly done from their spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electromagnetic Spectrum
The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies. The electromagnetic spectrum covers electromagnetic waves with frequencies ranging from below one hertz to above 1025 hertz, corresponding to wavelengths from thousands of kilometers down to a fraction of the size of an atomic nucleus. This frequency range is divided into separate bands, and the electromagnetic waves within each frequency band are called by different names; beginning at the low frequency (long wavelength) end of the spectrum these are: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays at the high-frequency (short wavelength) end. The electromagnetic waves in each of these bands have different characteristics, such as how they are produced, how they interact with matter, and their practical applications. There is no known limit for long and short wavelengths. Extreme ultr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rossi X-ray Timing Explorer
The Rossi X-ray Timing Explorer (RXTE) was a NASA satellite that observed the time variation of astronomical X-ray sources, named after physicist Bruno Rossi. The RXTE had three instruments — an All Sky Monitor, the High-Energy X-ray Timing Experiment (HEXTE) and the Proportional Counter Array. The RXTE observed X-rays from black holes, neutron stars, X-ray pulsars and X-ray bursts. It was funded as part of the Explorer program, and was also called Explorer 69. RXTE had a mass of and was launched from Cape Canaveral on 30 December 1995, at 13:48:00 UTC, on a Delta II launch vehicle. Its International Designator is 1995-074A. Mission The X-Ray Timing Explorer (XTE) mission has the primary objective to study the temporal and broad-band spectral phenomena associated with stellar and galactic systems containing compact objects in the energy range 2--200 KeV, and in time scales from microseconds to years. The scientific instruments consists of two pointed instruments, the Pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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