Institution: | Departamento de Astromomia y Astrofisica, P. Universidad Catolica, Avenida Vicuna Mackenna 4860, Casilla 306, Santiago 22, Chile;Institute of Astronomy, Madingley Road, Cambridge CB3 0HA;Blackett Laboratory, Imperial College of Science Technology and Medicine, Prince Consort Road, London SW7 2BZ;Anglo-Australian Observatory, PO Box 296, Epping, NSW 1710, Australia |