Shot Owens was the 11th nuclear detonation of Operation Plumbbob, fired on 25 July 1957 from a 152-metre plastic balloon above Area 9b of the Nevada Test Site. It was a University of California Radiation Laboratory developmental test of a very small boosted plutonium device — the direct progenitor of the XW-51 warhead. With a nuclear system compact enough to fit into a tactical rocket, the XW-51 lineage led to the W-51 warhead subsequently deployed in the MGR-1 Honest John — an unguided surface-to-surface battlefield rocket with a range of approximately 37 kilometres. Owens produced 9.7 kilotons against a predicted range of 2–10 kilotons, placing its actual yield at the upper end of expectations. This Lookout Mountain Air Force Station photograph — AEC-57-7993 — documents the Owens fireball, explicitly captioned as such. The device was suspended from a plastic balloon rather than the conventional systems used in other Plumbbob shots. Following UCRL's naming convention of North American geographical features, Owens takes its name from the Owens Valley region of eastern California.