Shot Fizeau was the 19th nuclear detonation of Operation Plumbbob, fired on 14 September 1957 at 09:45 PDT from a 152-metre tower in Area 3b of Yucca Flat, Nevada Test Site. It was a Los Alamos Scientific Laboratory boosted fission device — compact and lightweight at just 59 kg total, 40 centimetres in diameter and 80 centimetres long — possibly a development test of the XW-34 depth bomb, an anti-submarine warfare warhead. The shot produced 11 kilotons against a predicted yield of 8–10 kt. The cloud ascended to approximately 12,200 metres. Fizeau is named for the French physicist Hippolyte Fizeau (1819–1896), known for the first accurate terrestrial measurement of the speed of light.