Projection of the measurement of the medium temperature extracted from thermal dileptons in p-Pb collisions. As the expected signal is uncertain, the figure presents the required integrated luminosity relative to the prediction based on Ref.~\cite{Rapp:2011is} denoted by N(Rapp). It is expressed as the minimum thermal photon N(thermal radiation) to $\pi^0$ ratio (left axis) and scaling of N(thermal radiation) (right axis) for achieving a 10\% statistical uncertainty on the extracted temperature.