ARECIBO OBSERVATORY

The Arecibo Observatory is a radio telescope near the city of Arecibo in Puerto Rico. It is operated by SRI International under cooperative agreement with the National Science Foundation.The observatory is also called the National Astronomy and Ionosphere Center, although "NAIC" refers to both the observatory and the staff that operate it.. Arecibo Observatory radio-astronomy facility includes the world's  Largest single-dish radio telescope. Conceived by, designed by, and built under the supervision of William E. Gordon, it was completed in 1963 and is now operated by SRI International and its partners under contract with the U.S. National Science Foundation..
Suspended 450 feet above the reflector is the 900 ton platform. Similar in design to a bridge, it hangs in midair on eighteen cables, which are strung from three reinforced concrete towers. One is 365 feet high, and the other two are 265 feet high. All three tops are at the same elevation. The combined volume of reinforced concrete in all three towers is 9,100 cubic yards. Each tower is back-guyed to ground anchors with seven 3.25 inch diameter steel bridge cables. Another system of three pairs of cables runs from each corner of the platform to large concrete blocks under the reflector. They are attached to giant jacks which allow adjustment of the height of each corner with millimeter precision.

The observatory's 305 m (1,000 ft) radio telescope is the largest single-aperture telescope (cf. multiple aperture telescope) ever constructed. It carries out three major areas of research: radio astronomy, aeronomy (using both the 305 m telescope and the observatory's lidar facility), and radar astronomy observations of Solar System objects. Scientists who want to use the telescope submit proposals, which are evaluated by an independent board.

Visually distinctive, the telescope makes frequent appearances in motion picture and television productions. The telescope received additional international recognition in 1999 when it began to collect data for the SETI@home project.

The center was listed on the U.S. National Register of Historic Places in 2008. It was the featured listing in the National Park Service's weekly list of October 3, 2008. The center was named an IEEE Milestone in 2001.