ANISOTROPY IN THE ANGULAR BROADENING OF SAGITTARIUS A-ASTERISK AT THEGALACTIC-CENTER

We present the results of a lambda = 20 cm VLA2 observation of the com pact Galactic center radio source Sgr A. The scatter-broadened image is elongated in the east-west direction, with an axial ratio of 0.56 /- 0.22 and a position angle of 82-degrees +/- 1-degree.8. A similar s hape and orientation has been found previously at shorter wavelengths using VLBI and VLBA. Both the major and minor axes follow the lambda2 law appropriate for scattering by turbulence in the intervening medium . We argue that the scattering occurs in thin ionized surface layers o f molecular clouds lying in the central 100 pc of the Galaxy. The ioni zed regions are characterized by electron densities of 10(4) cm -3 and milligauss magnetic field strengths, and are responsible for the diff use free-free emission and the Faraday rotation in the region.