Magnetars actually were first detected in 1979, but their mechanism was not comprehended then. In March of that year, gamma ray detectors around the world suddenly began to ring off the wall. A gamma ray burst of unprecedented intensity flooded Earth. It lasted just 2/10ths of a second, but was followed by a 100 second tailing off.
Interestingly, Dr. Chryssa Kouveliotou, working on her Doctorate in Astrophysics at the Max Planck Institute, was one of the researchers who detected this burst.
With so many detectors picking up the burst, it was easy to pinpoint its location. But scientists could scarcely believe their data. If the location was correct, the intensity of the bursts were even stronger than originally thought.
The triangulation data said unequivocally that the burst came from the Large Magellanic Cloud (LMC). That is a satellite galaxy of our Milky Way about 160,000 lys away. If the burst did indeed come from there, it had to be immensely strong.
The data was irrefutable. The burst came from a pulsar in the LMC.
A few years later, astrophysicists selected a name for these phenomenon—Soft Gamma Ray Repeaters or SGRs, because the gamma rays are ‘soft’ as opposed to ‘hard gamma rays’ such as given off by a nuclear bomb.