Located in M81, a spiral galaxy in the constellation Ursa Major, the distance of this supernova from Earth is estimated to be 11 million light-years. Its proximity and its radio emission level have offered a unique opportunity for very long baseline interferometry studies. Using radio antennas in the Very Long Baseline Array, the Very large Array, and various tracking stations around the world, astronomers have been able to study the structure of the supernova in detail. By observing at regular intervals, they have produced this sequence of images showing a shell-like radio structure that has expanded for five years with circular symmetry. At first the expansion rate was nearly 10,000 miles per second, but recently it has begun to suffer deceleration.
Radio emissions appear stronger on one side of the shell than the other.
Through continued observation and study, scientists hope to learn more about this supernova as it changes over time.