The results of an extremely deep , 8-day long observation of the central kpc of the nearby starburst galaxy M82 using MERLIN ( Multi-Element Radio Linked Interferometer Network ) at 5 GHz are presented .
The 17 \mu Jy beam ^ { -1 } , rms noise level in the naturally weighted image make it the most sensitive high resolution radio image of M82 made to date .
Over 50 discrete sources are detected , the majority of which are supernova remnants , but with 13 identified as H ii regions .
Sizes , flux densities and radio brightnesses are given for all of the detected sources , which are all well resolved with a majority showing shell or partial shell structures .
Those sources within the sample which are supernova remnants have diameters ranging from 0.3 to 6.7 pc , with a mean size of 2.9 pc .

From a comparison with previous MERLIN 5 GHz observations made in July 1992 , which gives a 9.75 year timeline , it has been possible to measure the expansion velocities of ten of the more compact sources , eight of which have not been measured before .
These derived expansion velocities range between 2200 and 10500 km s ^ { -1 } .