Area 51 Nellis Bombing Range Test Site airport (KXTA) on the north of the Area 51 USAF military installation. The lake at elevation is approximately from north to south and from east to west at its widest point. Located within the namesake Groom Lake Valley portion of the Tonopah Basin, the lake is south of Rachel, Nevada. The origin of the Area 51 name is unclear. The most accepted comes from a grid numbering system of the area by the Atomic Energy Commission (AEC); while Area 51 is not part of this system, it is adjacent to Area 15. Another explanation is
Area 51 aerospace magazine "The Space Review" titled "Astronauts and Area 51: the Skylab Incident". The article was based on a memo written in 1974 to CIA director William Colby by an unknown CIA official. The memo reported that astronauts on board Skylab 4 had, as part of a larger program, inadvertently photographed a location of which the memo said: Although the name of the location was obscured, the context led Day to believe that the subject was Groom Lake. As Day noted: The memo details debate between federal agencies regarding whether the images should be classified, with Department of Defense agencies