Being the nearest supernova to have been detected in the last 400 years, SN 1987A in the LMC has provided a unique opportunity to study not only a supernova event and its aftermath, but also the progenitor star and its circumstellar medium. MOST observations at 843 MHz have provided the most comprehensive time sampling of the radio emission, and the history of the observations up to September 1994 has been reported. A brief radio outburst was detected a few days after the explosion, but subsequent redetection, by both the MOST and ATCA, did not occur until mid 1990. The sudden increase of radio emission several years after the explosion could be due to the supernova shock encountering a sudden increase in the density of circumstellar material associated with past mass-loss history of the progenitor.
Optical observations suggest that the lobes correspond to the equatorial plane of the progenitor.
The remnant is expanding at about 3,000 km s, much more slowly than the initial shock velocity of around 30,000 km s. A model of the radio emission has been based on diffusive shock acceleration of electrons and ions by the supernova blast wave. 64-m telescope has been used in a survey of radio sources towards the LMC at frequencies of 1.40, 2.45, 4.75 and 8.55 GHz. Images and source lists from a MOST survey of the SMC are now available. One of the LMC objects, DEM L316, shows two overlapping shells.