The Sydney 19.7-MC Radio Telescope

The construction and operation of the Sydney 19.7mc "Mills Cross" radio telescope is described briefly, with special reference to the features peculiar to operation at this low frequency. The results obtained so far are reviewed. They relate to the detection of ionized interstellar hydrogen, to the evaluation of the general background radiation from extremely distant external galaxies, to the study of discrete sources, and to the study of refraction in the ionosphere.