>>11721688
Ah okay so they use multiple antennas
The radar images reveal an asteroid with a length of at least one mile (1.6 kilometers) and a shape similar to that of the exposed portion of a hippopotamus wading in a river. They were obtained Dec. 15-17 by coordinating the observations with NASA's 230-foot (70-meter) antenna at the Goldstone Deep Space Communications Complex in California, the National Science Foundation's 330-foot (100-meter) Green Bank Telescope in West Virginia and the Arecibo Observatory's 1,000-foot (305-meter) antenna in Puerto Rico.
The Green Bank Telescope was the receiver for the powerful microwave signals transmitted by either Goldstone or the NASA-funded Arecibo planetary radar in what is known as a "bistatic radar configuration." Using one telescope to transmit and another to receive can yield considerably more detail than would one telescope, and it is an invaluable technique to obtain radar images of closely approaching, slowly rotating asteroids like this one.
(Attached image) These two radar images of near-Earth asteroid 2003 SD220 were obtained on Dec. 18 and 19 by coordinating observations with the Arecibo Observatory's 1,000-foot (305-meter) antenna in Puerto Rico and the National Science Foundation's (NSF) 330-foot (100-meter) Green Bank Telescope in West Virginia.
Wonder how the quality is going to be now with the larger Arecibo not in the equation anymore.