Radio proper motions: Cas A & Kepler

We present a preliminary analysis of a new generation of proper motion measurements of the radio emission from the Cas A and Kepler supernova remnants. We utilized a cross-correlation type of measurement which is sensitive to features with a wine range of sizes and shapes. Initial results show a great deal of velocity structure in both remnants, superposed on their overall expansion. We find many inward-moving features in Cas A, and show the X-ray/radio velocity discrepancy in Kepler.