  We report on the detection of atomic oxygen lines in the spectra of 8 comets.
These forbidden lines are a result of the photodissociation of the parent
oxygen-bearing species directly into an excited state. We used high resolution
spectra obtained at the McDonald Observatory 2.7m telescope to resolve the
cometary oxygen lines from the telluric oxygen lines and from other cometary
emissions. We find that the relative intensities of the two red lines (6300.304
and 6363.776A) are consistent with theory. The green line (5577.339A) has an
intensity which is about 10% of the sum of the intensities of the two red
lines. We show that collisional quenching may be important in the inner coma.
If we assume the relative excitation rates of potential parents which have
appeared in the literature, then H2O would be the parent of the cometary green
oxygen line. However, those rates have been questioned. We measured the width
of the three oxygen lines and find that the green line is wider than either of
the two red lines. The finding of a wider line could imply a different parent
for the green and red lines. However, the constancy of the green to red line
flux ratio suggests the parent is the same for these lines but that the
exciting photons have different energies.
