In gamma-ray astronomy, gamma-ray bursts (GRBs) are immensely energetic explosions that have been observed in distant galaxies, being the brightest and most extreme explosive events in the entire universe, as NASA describes the bursts as the "most powerful class of explosions in the universe". They are the most energetic and luminous electromagnetic events since the Big Bang. Gamma-ray bursts can last from ten milliseconds to several hours. After the initial flash of gamma rays, an "afterglow" is emitted, which is longer lived and usually emitted at longer wavelengths.
Neil Gehrels Swift Observatory, previously called the Swift Gamma-Ray Burst Explorer, is a NASA three-telescope space observatory for studying gamma-ray bursts (GRBs) and monitoring the afterglow in X-ray, and UV/Visible light at the location of a burst. It was launched on 20 November 2004, aboard a Delta II launch vehicle. Headed by principal investigator Neil Gehrels until his death in February 2017, the mission was developed in a joint partnership between Goddard Space Flight Center (GSFC) and an international consortium from the United States, United Kingdom, and Italy. The mission is operated by Pennsylvania State University as part of NASA's Medium Explorer program (MIDEX).
GRB 970228 was the first gamma-ray burst (GRB) for which an afterglow was observed. It was detected on 28 February 1997 at 02:58 UTC. Since 1993, physicists had predicted GRBs to be followed by a lower-energy afterglow, but until this event, GRBs had only been observed in highly luminous bursts of high-energy gamma rays ; this resulted in large positional uncertainties which left their nature very unclear.
GRB 080319B was a gamma-ray burst (GRB) detected by the Swift satellite at 6:12 UTC on March 19, 2008. The burst set a new record for the farthest object that was observable with the naked eye: it had a peak visual apparent magnitude of 5.7 and remained visible to human eyes for approximately 30 seconds. The magnitude was brighter than 9.0 for approximately 60 seconds. If viewed from 1 AU away, it would have had a peak apparent magnitude of −67.57. It had an absolute magnitude of −38.6, beaten by GRB 220101A with −39.4 in 2023.
GRB 080913 was a gamma-ray burst (GRB) observed on September 13, 2008. The Swift Gamma-Ray Burst satellite made the detection, with follow-up and additional observations from ground-based observatories and instruments, including the Gamma-Ray Burst Optical/Near-Infrared Detector (GROND) and the Very Large Telescope. At 12.8 billion light-years and redshift of 6.7, the burst was the most distant GRB observed until GRB 090423 on April 23, 2009. This stellar explosion occurred around 825 million years after the Big Bang.
GRB 080916C is a gamma-ray burst (GRB) that was recorded on September 16, 2008, in the Carina constellation and detected by NASA's Fermi Gamma-ray Space Telescope. The burst lasted for 23 minutes. It is one of the most extreme gamma-ray bursts ever recorded, and was the most energetic gamma-ray burst ever recorded, until GRB 221009A was recorded in 2022. The explosion had the energy of approximately 9,000 type Ia supernovae if the emission was isotropically emitted, and the gas jets emitting the initial gamma rays moved at a minimum velocity of approximately 299,792,158 m/s, making this blast one of the most extreme recorded.
The Gamma-Ray Burst Optical/Near-Infrared Detector (GROND) is an imaging instrument used to investigate Gamma-Ray Burst afterglows and for doing follow-up observations on exoplanets using transit photometry. It is operated at the 2.2-metre MPG/ESO telescope at ESO's La Silla Observatory in the southern part of the Atacama desert, about 600 kilometres north of Santiago de Chile and at an altitude of 2,400 metres.
GRB 970508 was a gamma-ray burst (GRB) detected on May 8, 1997, at 21:42 UTC; it is historically important as the second GRB with a detected afterglow at other wavelengths, the first to have a direct redshift measurement of the afterglow, and the first to be detected at radio wavelengths.
The history of gamma-ray began with the serendipitous detection of a gamma-ray burst (GRB) on July 2, 1967, by the U.S. Vela satellites. After these satellites detected fifteen other GRBs, Ray Klebesadel of the Los Alamos National Laboratory published the first paper on the subject, Observations of Gamma-Ray Bursts of Cosmic Origin. As more and more research was done on these mysterious events, hundreds of models were developed in an attempt to explain their origins.
GRB 090423 was a gamma-ray burst (GRB) detected by the Swift Gamma-Ray Burst Mission on April 23, 2009, at 07:55:19 UTC whose afterglow was detected in the infrared and enabled astronomers to determine that its redshift is z = 8.2, making it one of the most distant objects detected at that time with a spectroscopic redshift.
GRB 990123 is a gamma-ray burst which was detected on January 23, 1999. It was the first GRB for which a simultaneous optical flash was detected. Astronomers first managed to obtain a visible-light image of a GRB as it occurred on January 23, 1999, using the ROTSE-I telescope in Los Alamos, New Mexico. The ROTSE-I was operated by a team under Dr. Carl W. Akerlof of the University of Michigan and included members from Los Alamos National Laboratory and Lawrence Livermore National Laboratory. The robotic telescope was fully automated, responding to signals from NASA's BATSE instrument aboard the Compton Gamma Ray Observatory within seconds, without human intervention. In the dark hours of the morning of January 23, 1999, the Compton satellite recorded a gamma-ray burst that lasted for about a minute and a half. There was a peak of gamma and X-ray emission 25 seconds after the event was first detected, followed by a somewhat smaller peak 40 seconds after the beginning of the event. The emission then fizzled out in a series of small peaks over the next 50 seconds, and eight minutes after the event had faded to a hundredth of its maximum brightness. The burst was so strong that it ranked in the top 2% of all bursts detected.
Gamma-ray astronomy is a subfield of astronomy where scientists observe and study celestial objects and phenomena in outer space which emit cosmic electromagnetic radiation in the form of gamma rays, i.e. photons with the highest energies at the very shortest wavelengths. Radiation below 100 keV is classified as X-rays and is the subject of X-ray astronomy.
GRB 000131 was a gamma-ray burst (GRB) that was detected on 31 January 2000 at 14:59 UTC. A gamma-ray burst is a highly luminous flash associated with an explosion in a distant galaxy and producing gamma rays, the most energetic form of electromagnetic radiation, and often followed by a longer-lived "afterglow" emitted at longer wavelengths.
GRB 020813 was a gamma-ray burst (GRB) that was detected on 13 August 2002 at 02:44 UTC. A gamma-ray burst is a highly luminous flash associated with an explosion in a distant galaxy and producing gamma rays, the most energetic form of electromagnetic radiation, and often followed by a longer-lived "afterglow" emitted at longer wavelengths.
GRB 070714B was a gamma-ray burst (GRB) that was detected on 14 July 2007 at 4:59 UTC. A gamma-ray burst is a highly luminous flash associated with an explosion in a distant galaxy and producing gamma rays, the most energetic form of electromagnetic radiation, and often followed by a longer-lived "afterglow" emitted at longer wavelengths.
GRB 101225A, also known as the "Christmas burst", was a cosmic explosion first detected by NASA's Swift observatory on Christmas Day 2010. The gamma-ray emission lasted at least 28 minutes, which is unusually long. Follow-up observations of the burst's afterglow by the Hubble Space Telescope and ground-based observatories were unable to determine the object's distance using spectroscopic methods.
GRB 130427A was a record-setting gamma-ray burst, discovered starting on April 27, 2013. This GRB was associated to SN 2013cq, of which the appearance of optical signal was predicted on May 2, 2013 and detected on May 13, 2013. The Fermi space observatory detected a gamma-ray with an energy of at least 94 billion electron volts. It was simultaneously detected by the Burst Alert Telescope aboard the Swift telescope and was the brightest burst Swift had ever detected. It was one of the five closest GRBs, at about 3.6 billion light-years away, and was comparatively long-lasting.
Fermi's Large Area Telescope (LAT) recorded one gamma ray with an energy of at least 94 billion electron volts (GeV), or some 35 billion times the energy of visible light, and about three times greater than the LAT's previous record. The GeV emission from the burst lasted for hours, and it remained detectable by the LAT for the better part of a day, setting a new record for the longest gamma-ray emission from a GRB.
The Space Variable Objects Monitor (SVOM) is a small X-ray telescope satellite developed by China National Space Administration (CNSA), Chinese Academy of Sciences (CAS) and the French Space Agency (CNES), launched on 22 June 2024.
The Ultra-Fast Flash Observatory (UFFO) Pathfinder is a space observatory measuring prompt emission of gamma-ray bursts (GRB) both in optical/UV and in X-ray range down to sub-second timescales for the first time. Instead of turning the whole satellite towards GRB location like the Swift Gamma-Ray Burst Mission, UFFO employs a slewing mirror telescope approach – the optical path of the telescope is changed by rotation of motorized mirror within ~1 second after burst was detected.
GRB 160625B was a bright gamma-ray burst (GRB) detected by NASA's Fermi Gamma-ray Space Telescope on 25 June 2016 and, three minutes later, by the Large Area Telescope. This was followed by a bright prompt optical flash, during which variable linear polarization was measured. This was the first time that these observations were made when the GRB was still bright and active. The source of the GRB was a possible black hole, within the Delphinus constellation, about 9 billion light-years (light travel distance) away (a redshift of z = 1.406). It had a fluence of 5.7×10−4 erg cm−2, and energy of 5 × 1054 erg. The burst lasted over 11 minutes (680 s), and was one of the most energetic bursts ever recorded.
