  The CN coma structure of the EPOXI mission target, comet 103P/Hartley 2, was
observed during twenty nights from September to December 2010. These CN images
probe the rotational state of the comet's nucleus and provide a ground-based
observational context to complement the EPOXI observations. A dynamically
excited cometary nucleus with a changing rotational rate is observed, a
characteristic not seen in any comet in the past. The lack of rotational
damping during the four-month observing interval places constraints on the
interior structure of the nucleus.
