  We present results from an HST study of the morphology and kinematics of NGC
6240. This merging galaxy with a double nucleus is one of the nearest and
best-studied ultraluminous infrared galaxies. HST resolves both nuclei into
seperate components. The distance between the northern and southern
optical/near-infrared components is greater than that observed in radio and
X-ray studies, arguing that even in K-band we may not be seeing all the way
through the dust to the true nuclei. The ionized gas does not display rotation
around either of the nuclei, or equilibrium motion in general. There is a
strong velocity gradient between the nuclei, similar to what is seen in CO
data. There is no such gradient in our stellar kinematics. The velocity
dispersion of the gas is larger than expected for a cold disk. We also map and
model the emission-line velocity field at an off-nuclear position where a steep
velocity gradient was previously detected in ground-based data. Overall, the
data indicate that line-of-sight projection effects, dust absorption,
non-equilibrium merger dynamics, and the possible influence of a wind may be
playing an important role in the observed kinematics. Chandra observations of
hard X-rays have shown that both of the nuclei contain an Active Galactic
Nucleus (AGN). The HST data show no clear sign of the two AGNs: neither
continuum nor narrow-band imaging shows evidence for unresolved components in
the nuclei, and there are no increased emission line widths or rapid rotation
near the nuclei. This underscores the importance of X-ray data for identifying
AGNs in highly dust-enshrouded environments.
