GRB 790305b is an event that took place on 5 March 1979. It was an extremely bright burst that was successfully localized to supernova remnant N49 in the

Large Magellanic Cloud The Large Magellanic Cloud (LMC), or Nubecula Major, is a satellite galaxy of the Milky Way. At a distance of around 50 kiloparsecs (≈160,000 light-years), the LMC is the second- or third-closest galaxy to the Milky Way, after the ...

. This event is now interpreted as a magnetar giant flare, more related to SGR flares than "true" gamma-ray bursts. It is the first observed SGR megaflare, a specific type of short GRB. It has been associated with the magnetar PSR B0525-66.

The event

On 5 March 1979, Soviet spacecraft

Venera 11 The Venera 11 (russian: Венера-11 meaning ''Venus 11'') was a Soviet uncrewed space mission which was part of the Venera program to explore the planet Venus. Venera 11 was launched on 9 September 1978 at 03:25:39 UTC. Separating from its ...

and

Venera 12 The Venera 12 (russian: Венера-12 meaning Venus 12) was an uncrewed Soviet space mission designed to explore the planet Venus. Venera 12 was launched on 14 September 1978 at 02:25:13 UTC. After separating from its flight platform on 19 ...

, then drifting through the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...

, were hit by a blast of gamma radiation at approximately 10:51 EST. This contact raised the radiation readings on both the probes from a normal 100 counts per second to over 200,000 counts a second, in only a fraction of a millisecond. This burst of gamma rays quickly continued to spread. Eleven seconds later, Helios 2, a

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

probe, which was in orbit around the Sun, was saturated by the blast of radiation. It soon hit Venus, and the

Pioneer Venus Orbiter The Pioneer Venus Orbiter, also known as Pioneer Venus 1 or Pioneer 12, was a mission to Venus conducted by the United States as part of the Pioneer Venus project. Launched in May 1978 atop an Atlas-Centaur rocket, the spacecraft was inserted into ...

's detectors were overcome by the wave. Seconds later, Earth received the wave of radiation, where the powerful output of gamma rays inundated the detectors of three U.S. Department of Defense

Vela satellites Vela was the name of a group of satellites developed as the Vela Hotel element of Project Vela by the United States to detect nuclear detonations to monitor compliance with the 1963 Partial Test Ban Treaty by the Soviet Union. Vela started out a ...

, the Soviet Prognoz 7 satellite, and the

Einstein Observatory Einstein Observatory (HEAO-2) was the first fully imaging X-ray telescope put into space and the second of NASA's three High Energy Astrophysical Observatories. Named HEAO B before launch, the observatory's name was changed to honor Albert E ...

. Just before the wave exited the Solar System, the blast also hit the International Sun-Earth Explorer. This extremely powerful blast of gamma radiation constituted the strongest wave of extra-solar gamma rays ever detected; it was over 100 times more intense than any known previous extra-solar burst. Because gamma rays travel at the speed of light and the time of the pulse was recorded by several distant spacecraft as well as on Earth, the source of the

gamma radiation 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 s ...

could be calculated to an accuracy of about 2

arcseconds A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...

. The direction of the source corresponded with the remnants of a star that had gone supernova around 3000 B.C.E.Kouveliotou, C.; Duncan, R. C.; Thompson, C. (February 2003).
Magnetars
". ''

Scientific American ''Scientific American'', informally abbreviated ''SciAm'' or sometimes ''SA'', is an American popular science magazine. Many famous scientists, including Albert Einstein and Nikola Tesla, have contributed articles to it. In print since 1845, it i ...

''; Page 36. It was in the

and the source was named SGR 0525-66, the event itself was named GRB 790305b, the first observed SGR megaflare.

References

{{DEFAULTSORT:GRB 790305b 19790305 Dorado (constellation) Large Magellanic Cloud 19790305 March 1979 events