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.
On March 5, 1979 a powerful gamma-ray burst was noted. As a number of receivers at different locations in the Solar System saw the burst at slightly different times, its direction could be determined, and it was shown to originate from near a supernova remnant in the Large Magellanic Cloud.
Over time it became clear that this was not a normal gamma-ray burst. The photons were less energetic in the soft gamma-ray and hard X-ray range, and repeated bursts came from the same region.
Astronomer Chryssa Kouveliotou of the Universities Space Research Association (USRA) at NASA's Marshall Space Flight Center decided to test the theory that soft gamma repeaters were magnetars.