This award will permit continuation of extremely productive studies of X-Ray selected active galactic nuclei (AGN), dense and distant clusters of galaxies, and BL Lacertae objects. These systems possess in common the characteristic that objects selected on the basis of their X-Ray emissions would not necessarily be identified on the basis of their luminosity in other wavelength regions. Dr. Stocke has been one of the leading contributors to studies of these systems, which appear to hold promise for increasing our understanding of such phenomena as cooling flows, evolution of galaxies, and beaming of radiation.
