\section{SNa discovery rates}

Simulations, \citet{Belokurov_et_al_2003} and updated by \citet{icella_Cappellaro_Turatto_2012}, predict Gaia will see $\sim$6000 SNe down to G=19 (3/day), and twice this to G=20. One SN per day will be brighter than 18th magnitude (see Fig~\ref{fig:SN_rate}). For cataclysmic variables (CVs) the rate will be approximately similar, and Breedt, (priv. comm) predict Gaia should find 1000 new CVs. \citet{Blagorodnova_in_prep_2014} predict that Gaia will find of order 20 Tidal disruption event's (TDE's) per year. Young stellar objects outbursts will be less common and Gaia will probably only find a few per year.
