Multi-frequency light curve of SN 2008iz. The MERLIN 5 GHz data were taken from Beswick et al. (2009) and the Urumqi 5 GHz from Marchili et al. (2010). The remaining data are tabulated in Tables A.1 and A.2. The black line represents a Weiler model fit to 5 GHz data obtained by Marchili et al. (2010) with the Urumqi telescope. The other lines represent light curves calculated using the equations in the text for the other frequency data sets as colour coded in the legend.