A New Model for the Radio Emission from SN 1994I and an Associated
  Search for Radio Transients in M51
  We revisit the exquisite archival radio data for the Type Ic supernova SN
1994I and present a revised model for the SN radio emission and a pilot study
that aims to constrain the rate of C-band radio transients within the face-on
host galaxy, M51 (NGC 5194). We find that the temporal and spectral evolution
of the SN\,1994I radio emission are well fit by a synchrotron self-absorption
model and use this to estimate physical parameters. We compute a pre-explosion
mass loss rate of $\dot{M}=3.0 \times 10^{-5} M_{\odot}$ yr$^{-1}$ for the
progenitor, consistent with those observed from galactic Wolf-Rayet stars. Our
model makes different assumptions for the dynamical model for the shockwave
interaction than the model previously published by \cite{weil11}, but our
$\dot{M}$ is consistent with theirs to within errors and assumptions. Drawing
from a subset of the archival radio observations from the Very Large Array
collected for the monitoring of SN\,1994I, we conduct a pilot study to search
for previously-unidentified transients. Data were primarily taken at a
frequency of 4.9 GHz and are logarithmic in cadence, enabling sensitivity to
transients with variability timescales ranging from days to months. We find no
new transient detections in 31 epochs of data, allowing us to place a $2\sigma$
upper limit of 17 deg$^{-2}$ for the source density of radio transients above
0.5 mJy ($L\gtrsim4\times10^{25}$ erg s$^{-1}$ Hz$^{-1}$ at the distance of
M51). This study highlights the feasibility of utilizing archival high-cadence
radio studies of supernova host galaxies to place constraints on the radio
transient rate as a function of luminosity in the local Universe.
