mag that we use here is a reasonable average as long as we keep in mind that it has an uncertainty of [$\sim\!\!$ ]{}0.3 mag which leads to an uncertainty of [$\sim\!\!$ ]{}30% in the absolute flux of each late-time spectrum. When this is combined in quadrature with the uncertainty from the photometric measurements, the total uncertainty in the absolute flux of each of our late-time spectra is [$\sim\!\!$ ]{}39%.

The late-time spectra and models are shown in Figure \[f:model\]; both models appear to fairly accurately reproduce the major features observed in the data. However, the emission near 4000 Åand the feature near 7700 Å seem somewhat suppressed in the models. In addition, the intensity of the feature near 8600 Å in the models is somewhat larger than that of the observed spectrum, leading to a small inconsistency in the position of the combined plus \[\] $\lambda$8727 emission.

Here we use the one-zone version of the model described by @Mazzali07:02ap. It requires an emitting nebula with an outer velocity of 4300 [km s$^{-1}$]{}, as determined from reproducing the width of the strongest emission lines (\[\], \], and \[\]). The spectrum is powered by [$\sim\!\!$ ]{}0.13 [M$_\sun$]{} of $^{56}$Ni. This is 