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	Gamma-ray Burst Real-time Sky Map
		No visible-light observations were made since the GRB is located in the sky too close to a bright star.\n\nA new and somewhat uncertain technique that uses the energy of the gamma rays to determine a distance found a ''pseudo redshift for this burst of z=1.3, or a distance of about 8.8 billion light years.
		There was a 10-second-long burst of high-energy gamma rays (which rose quickly to a peak, stayed there for a few seconds, then faded rapidly), followed by a 20-second blast of lower-energy gamma-rays.
		The burst was faint, with a flat emission (that is, constant brightness) of low-energy or ''softer'' gamma rays for 280 seconds.
	grb.sonoma.edu (18589 words)

	Gamma-Ray Burst Physics
		Gamma-ray bursts (GRB) are sudden, intense flashes of gamma-rays which, for a few blinding seconds, light up in an otherwise fairly dark gamma-ray sky.
		GRBs were first reported in 1973, based on 1969-71 observations by the Vela military satellites monitoring for nuclear explosions in verification of the Nuclear Test Ban Treaty.
		These afterglows in turn enabled the measurement of redshift distances, the identification of host galaxies, and the confirmation that GRB were, as suspected, at cosmological distances of the order of billions of light-years, similar to those of the most distant galaxies and quasars.
	www.astro.psu.edu /users/nnp/grbphys.html (923 words)

	Welcome to the Swift Gamma Ray Burst Explorer Mission
		The Swift Gamma Ray Burst Explorer carries three instruments to enable the most detailed observations of gamma ray bursts to date.
		The XRT and UVOT are X-ray and a UV/optical focusing telescopes respectively which produce sub-arcsecond positions and multiwavelength lightcurves for gamma ray Burst (GRB) afterglows.
		The positions and images derived by the various instruments are sent as soon as they are available from the spacecraft via the TDRSS system to the Gamma Ray Coordination Network (GCN).
	www.swift.psu.edu (253 words)

	Closest Gamma Ray Burst
		As they move farther from the burst, their motion should be detected as a change in their position in the sky.
		Gamma Ray Bursts were first detected in 1967 by a satellite monitoring compliance with the 1963 atmospheric nuclear test-ban treaty.
		Once scientists determined that GRBs originate in distant galaxies and that they probably occur in regions of those galaxies where stars are actively forming, some 200 proposed models for what causes GRBs were reduced to a handful of viable models.
	www.nrao.edu /pr/2003/grb030329 (961 words)

	Gamma-ray Burst FAQ (Site not responding. Last check: 2007-10-13)
		Gamma ray bursts (GRBs for short) are intense and short (approximately 0.1-100 seconds long) bursts of gamma-ray radiation that occur all over the sky approximately once per day at very large distances from Earth.
		Gamma rays are very energetic photons (E>10^5 eV), which represent the most extreme portion of the electromagnetic spectrum (ranging from radio waves at the lowest energies through visible optical light at higher energies, to gamma rays at the highest energies).
		Recently, we have found the best evidence for the association of GRBs and supernovae based on optical and radio observations of GRB 011121, which showed a clear re-brightening of the optical light and a direct signature of the environment that is usually found around massive stars (which are the progenitors of both GRBs and supernovae).
	astro.caltech.edu /~ejb/faq.html (2713 words)

	Gamma Ray Burst Page
		Gamma-ray bursts were discovered in the late 1960s, but only recently have most astronomers agreed that a large fraction of the bursts originate in the very distant, early Universe.
		One of many explanations for gamma ray bursts is a hypernova, an exploding star a hundred times more powerful that a typical exploding star, called a supernova.
		Gamma ray bursts occur randomly several times a day without warning, last only a few seconds to a minute, and release more energy than any event in the Universe other than the Big Bang.
	www.gsfc.nasa.gov /gsfc/spacesci/gamma/gamma.htm (915 words)

	CNN - Hubble views fading gamma ray burst - March 17, 1999
		The initial explosion came as an intense burst of gamma rays on January 23, 1999.
		For a moment, light from the burst was equal to the radiance of 100 million billion stars.
		Gamma rays, which have long been elusive and mysterious, go off about once a day.
	www.cnn.com /TECH/space/9903/17/hubble.gamma.ray/index.html (349 words)

	The Cosmic Gamma Ray Burst Web Page (Site not responding. Last check: 2007-10-13)
		The primary objective of BATSE was to study the phenomenon of gamma-ray bursts, although the detectors also recorded data from pulsars, terrestrial gamma-ray flashes, soft gamma repeaters, fl holes, and other exotic astrophysical objects.
		Gamma ray bursts were discovered by accident in the 1960's, and for the past 30 years they've been the target of intense research and speculation by astronomers.
		BATSE was designed specifically for the study of the enigmatic gamma ray bursters and has led to a new understanding of their origin and distribution in the universe.
	www.batse.com (488 words)

	ESA - Space Science - Exploring space - A gamma-ray burst bonanza
		Such precision observations are providing scientists with a remarkable view of gamma-ray bursts, which occur randomly, fade within seconds, and yet shine with the intensity of millions upon millions of Suns.
		Scientists say that these bursts signal the birth of a brand new fl hole, either through the death of a massive star or through the merger of two neutron stars or fl holes.
		The bursts fade within seconds, never to appear in the same place twice, so scientists have been hard-pressed to study the bursts in detail.
	www.esa.int /export/esaSC/SEMIVX8YFDD_exploring_0.html (453 words)

	News in Science - Ray burst may have wiped out life on Earth - 29/04/2004
		Gamma-rays bursts (GRB) are extremely high-energy bursts of gamma-ray photons that shine millions of times brighter than the Sun.
		The researchers argued that a GRB from our own galaxy could have been "at least partly" responsible for a major mass extinction of coral, sponges and shelled organisms at the end of Ordovician period, about 440 million years ago.
		The researchers said the blast of energy from a GRB would have punched through the Earth's atmosphere and resulted in a powerful burst of UV radiation reaching the ground.
	www.abc.net.au /science/news/stories/s1097756.htm (754 words)

	Gamma-ray Burst Real-time Sky Map
		The Swift observatory is built to be agile, quickly turning to point its instruments at gamma-ray bursts and relaying the burst locations to the ground within seconds, much like the Swift bird might grab up insects as it flies through the sky.
		Within about 10 seconds of the burst trigger, the BAT produces a burst localization, which is transmitted to ground observers.
		Second, if a GRB is discovered by another telescope, the coordinates can be uploaded to Swift so that it can perform rapid observations of these bursts.
	grb.sonoma.edu /details.php?id=293 (910 words)

	Gamma ray burst - Wikipedia, the free encyclopedia
		Optical afterglow of gamma ray burst GRB-990123 (the bright dot within the white square and in the enlarged cutout) on 23 January 1999.
		A similar revolution in GRB astronomy is in progress today, largely as a result of the successful launch of NASA's Swift satellite, which combines a sensitive GRB detector with the ability to slew on-board X-ray and optical telescopes to the direction of a new burst in under one minute.
		GRBs themselves showed an extraordinary degree of diversity: they could be anywhere from a fraction of a second to many minutes in duration; bursts could have a single profile or oscillate wildly up and down in intensity; their spectra were highly variable and like nothing ever seen.
	en.wikipedia.org /wiki/Gamma_ray_burst (5438 words)

	NOVA Online \| Death Star \| A Bad Day in the Milky Way
		During the 1990s, the so-called Burst And Transient Source Experiment (BATSE), an instrument aboard NASA's orbiting Compton Gamma Ray Observatory, found that bursts lasting from fractions of a second to tens or hundreds of seconds occurred roughly once a day.
		The burst sources were clearly seen to lie in galaxies billions of light-years distant, confirming the enormous energies produced.
		Regardless of the mechanism producing the burst, the intense flux of gamma rays would likely be stopped in the lower stratosphere by collisions with atmospheric nitrogen molecules.
	www.pbs.org /wgbh/nova/gamma/milkyway.html (855 words)

	Gamma-rays
		Unlike optical light and X-rays, gamma rays cannot be captured and reflected in mirrors.
		Today, these gamma-ray bursts, which happen at least once a day, are seen to last for fractions of a second to minutes, popping off like cosmic flashbulbs from unexpected directions, flickering, and then fading after briefly dominating the gamma-ray sky.
		By solving the mystery of gamma-ray bursts, scientists hope to gain further knowledge of the origins of the Universe, the rate at which the Universe is expanding, and the size of the Universe.
	imagers.gsfc.nasa.gov /ems/gamma.html (722 words)

	Swift Gamma-Ray Burst Mission - Wikipedia, the free encyclopedia
		GRBs seem to take place at "cosmological distances," which means they can be used to probe the distant, and therefore young, universe.
		Swift had its first GRB trigger during a period when the autonomous slewing was enabled on January 17, 2005, at about 12:55 UT. It pointed the XRT telescope to the on-board computed coordinates and observed a bright source in the field of view.
		On February 18, 2006, Swift detected GRB 060218, an unusually long (about 2000 seconds) and nearby (about 440 million light years) burst which was unusually dim despite its close distance, and may be an indication of an imminent supernova.
	en.wikipedia.org /wiki/Swift_Gamma-Ray_Burst_Mission (1254 words)

	BBC NEWS \| Science/Nature \| Gamma-ray burst mystery solved
		After news of the latest burst was relayed around the world, astronomers working at the 6.5-metre Multiple Mirror Telescope (MMT) at Mount Hopkins in Arizona, US, were able to interrupt their schedule to look at the burster.
		The astronomers detected direct evidence that the afterglow of the burst exhibits the same patterns as light from a supernova.
		At the moment, researchers cannot yet determine the timing of the gamma burst relative to the supernova (whether one preceded the other or whether both began at the same time), but the same event - a star explosion - was certainly the trigger for both, they say.
	news.bbc.co.uk /2/hi/science/nature/2949735.stm (631 words)

	BBC NEWS \| Science/Nature \| Most distant cosmic blast sighted
		Gamma-ray bursts are intense flares of high-energy radiation that appear without warning from across the cosmos.
		The burst comes from an era soon after stars and galaxies first formed, about one billion years after the Big Bang.
		Scientists on four continents, using a variety of telescopes, have been tracking the burst and its afterglow as it gradually faded.
	news.bbc.co.uk /1/hi/sci/tech/4237800.stm (591 words)

	NASA - Top Story - RACE TO GAMMA-RAY BURST REVEALS GIGANTIC EXPOSION, DEATH & BIRTH - March 19, 2003
		Scientists arriving on the scene of a gamma-ray burst just moments after the explosion, have witnessed the death of a gigantic star and the birth of something monstrous in its place, quite possibly a brand new, spinning fl hole.
		Wasting no time, HETE spotted the burst, nailed down a location, and notified observers worldwide within a few seconds, while the gamma rays were still pouring in.
		Gamma-ray burst hunters are greatly aided by three new developments: fast triggers from orbiting detectors; fast relays to observers worldwide via the Gamma-ray burst Coordinates Network; and fast responses from ground-based robotic telescopes.
	www.nasa.gov /centers/goddard/news/topstory/2003/0319hete.html (1582 words)

	BATSE Current Gamma-Ray Burst Catalog
		The BATSE Burst Team has a policy of making gamma-ray burst data available to the scientific community as soon as possible.
		Several of the GRB catalog tables are released to the public as they are generated and before publication as an official catalog.
		Describes the fraction of time a burst will be triggered on each of the trigger timescales as a function of GRB intensity.
	www.batse.msfc.nasa.gov /batse/grb/catalog/current (387 words)

	HubbleSite - Gamma-Ray Burst Found to be Most Energetic Event in Universe - 5/6/1998
		A team of astronomers has announced that a recently detected gamma-ray burst was as bright as the rest of the universe, releasing a hundred times more energy than previously theorized.
		This Hubble image of the GRB 971214 field was taken about four months after the burst, well after the afterglow had faded away.
		The extremely faint and distant object marked with an arrow is the host galaxy of the gamma-ray burst.
	hubblesite.org /newscenter/newsdesk/archive/releases/1998/17 (179 words)

	Scientists catch another gamma-ray burster in visible light
		The team also pinned down GRB 990510, as it is designated, in the southern hemisphere in a constellation known as the Chamaeleon, at right ascension of 13h38m, and a declination of -80 deg.
		With a refined location, several southern observatories were aimed at GRB990510 in search of an visible-light counterpart (because GRB 990510 is in the Southern Hemisphere, it cannot be seen by the ROTSE array that captured the Jan. 28, 1999, burst).
		As observed by BATSE, GRB990510 looks like two bursts with an initial burst lasting about 10 seconds, followed by a 30-second gap, and then another burst that trails off gradually until it makes a final hiccup about 90 second after the first flash of gamma rays.
	science.nasa.gov /newhome/headlines/ast18may99_1.htm (1178 words)

	Original discovery of gamma-ray bursts
		For the many attendees at the Fourth Huntsville Gamma Ray Burst Symposium, Ray Klebasabel described how he discovered gamma ray bursts as he was making sure that his detectors would not be fooled by mother nature.
		Three more soon followed, and starting with Vela 3, the gamma ray detectors were made of cesium iodide which scintillates - flashes with visible light - when gamma rays pass through it.
		Renamed the Compton Gamma Ray Observatory, it was launched in 1991 and joined a wide array of Earth satellites and deep space probes that carried much smaller detectors.
	science.msfc.nasa.gov /newhome/headlines/ast19sep97_2.htm (873 words)

	Gamma-ray bursts: Introduction to a Mystery
		Gamma-ray bursts are short-lived bursts of gamma-ray photons, the most energetic form of light.
		Lasting anywhere from a few milliseconds to several minutes, gamma-ray bursts (GRBs) shine hundreds of times brighter than a typical supernova and about a million trillion times as bright as the Sun, making them briefly the brightest source of cosmic gamma-ray photons in the observable Universe.
		GRBs are detected roughly once per day from wholly random directions of the sky.
	imagine.gsfc.nasa.gov /docs/science/know_l1/bursts.html (396 words)

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