ac meaning in Computing ?

Ascension Island is an isolated volcanic island, 7°56′ south of the Equator in the South Atlantic Ocean. It is about 1,000 miles (1,600 km) from the coast of Africa and 1,400 miles (2,300 km) from the coast of Brazil. It is governed as part of the British Overseas Territory of Saint Helena, Ascension and Tristan da Cunha, of which the main island, Saint Helena, is around 800 miles (1,300 km) to the southeast. The territory also includes the sparsely populated Tristan da Cunha archipelago, 2,300 miles (3,700 km) to the south, about halfway to the Antarctic Circle.

Named after the day of its recorded discovery, Ascension of Jesus, Ascension Island was an important safe haven as a coaling station to mariners and a refueling stop for commercial airliners back in the days of international air travel by flying boats.

During World War II, it was an important naval and air station, especially providing antisubmarine warfare bases in the Battle of the Atlantic. Ascension Island was garrisoned by the British Admiralty from 22 October 1815 to 1922.

The island is the location of RAF Ascension Island, which is a Royal Air Force station, a European Space Agency rocket tracking station, an Anglo-American signals intelligence facility and the BBC World Service Atlantic Relay Station. The island was used extensively as a staging point by the British military during the Falklands War. Ascension Island hosts one of four ground antennas that assist in the operation of the Global Positioning System (GPS) navigational system (the others are on Kwajalein Island, Diego Garcia, and Cape Canaveral). NASA operates a Meter Class Autonomous Telescope (MCAT) on Ascension Island for tracking orbital debris, which is potentially hazardous to operating spacecraft and astronauts, at a facility called the John Africano NASA/AFRL Orbital Debris Observatory.