HST proper-motion measurements of η Carinae

We discuss the proper motions of equatorial disk and bipolar lobe material ejected from eta Carinae during the last century and deduce their relative ages in order to determine the likelihood of multiple ejection events. F336W HST images spanning a 626-day baseline from 1995 to 1997 were compared and the motions of small (1 ".16) patches throughout the nebulae were measured. Assuming that the material has not been decelerated, the expansion velocities of material in both lobes and in two equatorial features (the 'Paddle' and the 'El' region at the base of the NE jet) indicate that the bipolar lobes and equatorial ejecta have the same origin date - i.e., are the result of a single ejection event that occurred some 150 years ago during the Great Eruption. These results are consistent with the measurements of Currie et al. (1996, see also these proceedings) using a different set of HST images, but contrary to the findings of Smith & Gehrz (1998, see also these proceedings), who claim that the kinematic age of the equatorial debris is 30% younger than that of the bipolar lobes based on ground-based images spanning several decades.