Evolution of the blastwave radius as function of time, as measured from the video (see Fig. \ref{279461}). The Sedov-Taylor solution has one single parameter (the initial blast energy \(E_0\)) which we determined fitting the observed data. The best fit is obtained for \(E_0=7.5\) kilotons, in good agreement with the energy declared by LNLL for this experiment (7 kilotons).