Left panels: optical-to-MIR pseudo-bolometric lightcurve (upper left panel) and photospheric velocities (lower left panel) for the best-fit model (solid line) compared to observations (circles), where the photospheric velocities have been estimated from the absorption minimum of the Fe ii 5169 Å line. Observations not included in the fit are shown in grey. Right panels: contour plots showing the (grey-scale coded) standard deviation in the fit, normalized to that of the best-fit model, projected onto the E−M_He plane for the case where the photospheric velocities were used (upper right panel) and not used (lower right panel). We also show the constraints M_ej/E = const. (blue line) and /E = const. (red line) provided by the photospheric velocities and the bolometric lightcurve, respectively (E15).