by this time and has quite strong \[\] $\lambda\lambda$6300, 6364 and \] $\lambda$4571 emission. These and other common nebular SN features are marked in Figure \[f:late\_spec\]; the features of SNe 2001ig, 2002ap, and 1993J are all similar, but the relative strengths of some of the emission lines differ.

One of the most notable differences among the objects is that SN 1993J exhibits obvious [H$\alpha$]{}emission by day 298, appearing as a shoulder on the red wing of \[\] $\lambda\lambda$6300, 6364. @Filippenko94 and @Matheson00 showed that the [H$\alpha$]{} feature gradually strengthened from this time onward in SN 1993J, whereas in spectra at similar epochs of [SN 2001ig]{} shown in Figure \[f:late\_spec\] there is no obvious [H$\alpha$]{} emission. For SN 1993J the hydrogen at late times was attributed to interaction with circumstellar gas, but in [SN 2001ig]{} we see no evidence for such an interaction.

Figure \[f:late\_spec\] also shows that the blended \[\] emission near 5200 Å is weak, which indicates a relatively small $^{56}$Ni mass (see §\[s:model\] for more information on the mass of the ejecta). The line profiles of \] $\lambda$4571, \[\] $\lambda\lambda$6300, 6364, and \[\] $\lambda\lambda$7291, 7324 in the spectra of [SN 2001ig]{} in Figure \[f:late\_spec\] are quite strong and 