We report on our second-epoch VLBI and VLA observations of the Type Ib/c supernova 2001em , five years after the explosion .
It was suggested that SN 2001em might be a jet-driven gamma ray burst ( GRB ) , with the jet oriented near the plane of the sky , which would entail relativistic expansion or motion .
Our VLBI image shows that SN 2001em is still unresolved five years after the explosion .
For a distance of 83 Mpc ( H _ { 0 } = 70 km s ^ { -1 } Mpc ^ { -1 } ) , the nominal expansion velocity is 5800 \pm 10 , 000 km s ^ { -1 } , and the proper motion is 33 , 000 \pm 34 , 000 km s ^ { -1 } .
Our values are inconsistent with either relativistic expansion or motion , but are consistent with the non-relativistic expansion speeds and small proper motions seen in other supernovae .
In particular these values are consistent with radio emission from SN 2001em being due to normal , non-relativistic supernova ejecta interacting with the circumstellar medium .
Our VLA observations show a power-law decay in flux density since the time of the peak in the 8.4 GHz radio lightcurve in \sim 2003 .