GRB 790305b was a

gamma-ray burst In gamma-ray astronomy, gamma-ray bursts (GRBs) are extremely energetic events occurring in distant Galaxy, galaxies which represent the brightest and most powerful class of explosion in the universe. These extreme Electromagnetic radiation, ele ...

that occurred 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) is a dwarf galaxy and satellite galaxy of the Milky Way. At a distance of around , the LMC is the second- or third-closest galaxy to the Milky Way, after the Sagittarius Dwarf Spheroidal Galaxy, Sagittarius Dwarf ...

. This event is now interpreted as a

magnetar A magnetar is a type of neutron star with an extremely powerful magnetic field (~109 to 1011 T, ~1013 to 1015 G). The magnetic-field decay powers the emission of high-energy electromagnetic radiation, particularly X-rays and gamma rays.Ward; Br ...

giant flare, more related to

soft gamma repeater A soft gamma repeater (SGR) is an astronomical object which emits large bursts of gamma-rays and X-rays at irregular intervals. It is conjectured that they are a type of magnetar or, alternatively, neutron stars with fossil disks around them. H ...

(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 and Venera 12, then in

heliocentric orbit A heliocentric orbit (also called circumsolar orbit) is an orbit around the barycenter of the Solar System, which is usually located within or very near the surface of the Sun. All planets, comets, and asteroids in the Solar System, and the Sun ...

, 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. Eleven seconds later, Helios 2, a

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

probe, also in helio-orbit, 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 NASA 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 The United States Department of Defense (DoD, USDOD, or DOD) is an executive department of the U.S. federal government charged with coordinating and supervising the six U.S. armed services: the Army, Navy, Marines, Air Force, Space Force, t ...

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

, 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 HEAO Program, High Energy Astrophysical Observatories. Named HEAO B before launch, the observatory's name was changed to ho ...

. The Earth's

ionosphere The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays ...

expanded. The blast was also detected by the International Sun-Earth Explorer in distant

halo orbit A halo orbit is a periodic, non-planar orbit associated with one of the L1, L2 or L3 Lagrange points in the three-body problem of orbital mechanics. Although a Lagrange point is just a point in empty space, its peculiar characteristic is th ...

. This event was over 100 times more intense than any known previous extra-solar burst. Because gamma rays travel at the speed of light and the exact time of the detection pulse was recorded by several distant, widely dispersed spacecraft as well as on Earth, the source of the

gamma radiation A gamma ray, also known as gamma radiation (symbol ), is a penetrating form of electromagnetic radiation arising from high energy interactions like the radioactive decay of atomic nuclei or astronomical events like solar flares. It consists o ...

could be triangulated to within an accuracy of approximately 2

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

. The direction of the source corresponded with SGR 0525-66, the remnant of a star in the

that had exploded as a 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 scientists, including Albert Einstein and Nikola Tesla, have contributed articles to it, with more than 150 Nobel Pri ...

''; Page 36.

References

{{DEFAULTSORT:GRB 790305b 19790305 Dorado Large Magellanic Cloud 19790305 March 1979