On July 19, 1957, five men stood at Ground Zero of an atomic test that was being conducted at the Nevada Test Site. This was the test of a 2KT (kiloton) MB-1 nuclear air-to-air rocket launched from an F-89 Scorpion interceptor. The nuclear missile detonated 10,000 ft above their heads.
This was Operation Plumbbob John, July 19, 1957.
This weapon was later known as AIR-2 Genie. Most sources give the yield as 1.5 KT and the height of this detonation as 18-20K feet. The Genie was deployed operationally on F-89, F-101, and F-106 interceptors. Over 3000 were made and it remained in service until the last F-106 was retired in 1986.