Rotary cannon pointing out the tail of a B-52H.
Grand Forks Air Force Base (GFAFB) 'Friends And Neighbors Day' on May 27th 1989.
The M61 Vulcan is a hydraulically or pneumatically driven, six-barrel, air-cooled, electrically fired Gatling-style rotary cannon which fires 20 mm rounds at an extremely high rate (typically 6,000 rounds per minute). The M61 was originally produced by General Electric, and is currently produced by General Dynamics. (Wikipedia)