  A faint new radio source has been detected in the nuclear region of the
starburst galaxy M82 using MERLIN radio observations designed to monitor the
flux density evolution of the recent bright supernova SN2008iz. This new source
was initially identified in observations made between 1-5th May 2009 but had
not been present in observations made one week earlier, or in any previous
observations of M82. In this paper we report the discovery of this new source
and monitoring of its evolution over its first 9 months of existence. The true
nature of this new source remains unclear, and we discuss whether this source
may be an unusual and faint supernova, a supermassive blackhole associated with
the nucleus of M82, or intriguingly the first detection of radio emission from
an extragalactic microquasar.
