SATCOM 47 was a communications satellite in Earth orbit in the late 20th century. Owned and operated by Chronowerx Industries, it was augmented with technology which Henry Starling, Chronowerx's CEO, had cannibalized from the 29th century timeship Aeon.
In 1996, Starling's assistant H. Dunbar accessed the satellite and used it to locate Starling, who had been detained on the USS Voyager by Captain Kathryn Janeway. Locating him, he was able to use the Aeon to penetrate Voyager's shields with a transporter beam and retrieve Starling. (VOY: "Future's End, Part II")