Castalia . Asteroid 4769 . Asteroid 4769 Castalia is a near-Earth crossing asteroid that was discovered by Eleanor F. Helin (Caltech) on August 9, 1989. Scientists used radio astronomy and computer modeling to generate this image of Castalia. They obtained the data for the computer model in 1989 using the Arecibo radar/radio telescope in Puerto Rico when the asteroid passed within 5.6 million kilometers (3.5 million miles) of the Earth. ... Topographic Map of Castalia . ...