Microwave and X-Ray Constraints on Local Large-Scale Overdensities

We discuss the small scale temperature fluctuations of the microwave, background induced by a local overdensity, of size larger than the Local Supercluster, that may eventually account for a substantial fraction of the observed dipole anisotropy, and briefly mention the new prospects of observing them opened by space-borne experiments currently in project. We also show that useful information on the large scale distribution of galaxies and, in particular, on the correlation function of rich clusters can be elicited from an analysis of the HEAO 1 A-2 all sky survey data, exploiting also the spectral resolution of this experiment.