Kermit Beahan plutonium Urakami Valley Mitsubishi Big Stink Nagasaki Fat Man hypocenter Bockscar
At 11:01 Japanese Time, a last-minute break in the clouds over Nagasaki allowed Bockscar's bombardier, Captain Kermit Beahan, to visually sight the target as ordered. The Fat Man weapon, containing a core of about 5 kg (11 lb) of plutonium, was dropped over the city's industrial valley. It exploded 47 seconds later at 11:02 Japanese Time at 503 ± 10 m (1,650 ± 33 ft), above a tennis court, halfway between the Mitsubishi Steel and Arms Works in the south and the Nagasaki Arsenal in the north. This was nearly 3 km (1.9 mi) northwest of the planned hypocenter; the blast was confined to the Urakami Valley and a major portion of the city was protected by the intervening hills. The resulting explosion released the equivalent energy of 21 ± 2 kt (87.9 ± 8.4 TJ). Big Stink spotted the explosion from 160 kilometers (100 mi) away, and flew over to observe.
