  We have obtained optical spectrophotometry of the evolution of comet
9P/Tempel 1 after the impact of the Deep Impact probe, using the Supernova
Integral Field Spectrograph (SNIFS) at the UH 2.2m telescope, as well as
simultaneous optical and infrared spectra using the Lick
Visible-to-Near-Infrared Imaging Spectrograph (VNIRIS) spectrograph. The
spatial distribution and temporal evolution of the "violet band" CN (0-0)
emission and of the 630 nm [OI] emission was studied. We found that CN emission
centered on the nucleus increased in the two hours after impact, but that this
CN emission was delayed compared to the light curve of dust-scattered sunlight.
The CN emission also expanded faster than the cloud of scattering dust. The
emission of [OI] at 630 nm rose similarly to the scattered light, but then
remained nearly constant for several hours after impact. On the day following
the impact, both CN and [OI] emission concentrated on the comet nucleus had
returned nearly to pre-impact levels. We have also searched for differences in
the scattering properties of the dust ejected by the impact compared to the
dust released under normal conditions. Compared to the pre-impact state of the
comet, we find evidence that the color of the comet was slightly bluer during
the post-impact rise in brightness. Long after the impact, in the following
nights, the comet colors returned to their pre-impact values. This can be
explained by postulating a change to a smaller particle size distribution in
the ejecta cloud, in agreement with the findings from mid-infrared observatons,
or by postulating a large fraction of clean ice particles, or by a combination
of these two.

Astrophysics