  Comet 17P/Holmes underwent a massive outburst in 2007 Oct., brightening by a
factor of almost a million in under 48 hours. We used infrared images taken by
the Wide-Field Survey Explorer mission to characterize the comet as it appeared
at a heliocentric distance of 5.1 AU almost 3 years after the outburst. The
comet appeared to be active with a coma and dust trail along the orbital plane.
We constrained the diameter, albedo, and beaming parameter of the nucleus to
4.135 $\pm$ 0.610 km, 0.03 $\pm$ 0.01 and 1.03 $\pm$ 0.21, respectively. The
properties of the nucleus are consistent with those of other Jupiter Family
comets. The best-fit temperature of the coma was 134 $\pm$ 11 K, slightly
higher than the blackbody temperature at that heliocentric distance. Using
Finson-Probstein modeling we found that the morphology of the trail was
consistent with ejection during the 2007 outburst and was made up of dust
grains between 250 $\mu$m and a few cm in radius. The trail mass was $\sim$ 1.2
- 5.3 $\times$ 10$^{10}$ kg.
