The energetic cores of the nuclei of active galaxies can only be observed with instruments offering extremely high angular resolu- tion. This program utilizes the Very Large Array (VLA) and the techniques of Very Long Baseline Interferometry (VLBI) to inves- tigate three classes of these objects. BL Lacertae is a vio- lently varying radio source which has been identified with such a galactic core. VLBI observations of this object will be critical in testing a model of weak shocks propagating down an expanding relativistic flow which seems to fit past observations. Several candidates for the classification of 'compact double' will also be observed to test the hypotheses that these are 'young' sources which arise from recent tidal interactions. Finally, a high dynamic range map of the one-sided kiloparsec scale jet in 3C147 will be made to examine the idea that the one-sidedness is due to Doppler broadening. Dr. Mutel has been a leader in the application of Very Long Baseline Interferometry (VLBI) to astronomical problems and is the executive officer or the U. S. VLBI Consortium.
