  One of the goals of the Hubble Space Telescope program to observe periodic
comet 9P/Tempel 1 in conjunction with NASA's Deep Impact mission was to study
the generation and evolution of the gaseous coma resulting from the impact. For
this purpose, the Solar Blind Channel of the Advanced Camera for Surveys was
used with the F140LP filter which is sensitive primarily to the ultraviolet
emission (>1400 A) from the CO Fourth Positive system. Following the impact we
detected an increase in brightness, which if all due to CO corresponds to 1.5 x
10^31 molecules or a mass of 6.6 x 10^5 kg, an amount that would normally be
produced by 7-10 hours of quiescent outgassing from the comet. This number is
less than or equal to 10% of the number of water molecules excavated, and
suggests that the volatile content of the material excavated by the impact did
not differ significantly from the surface or near sub-surface material
responsible for the quiescent outgassing of the comet.
