Fat Man

The world's third atomic bomb, Fat Man, a plutonium implosion device explodes over Nagasaki, Japan. It has a yield of approximately 20 kilotons TNT. Some 35,000 to 40,000 persons die immediately, and a total of some 75,000 persons die from the bombing by the end of 1945. 

Fat Man was approximately 60 inches wide, 128 inches long, weight 10,300 lbs, and had a yield of 21 kilotons TNT.  The picture depicts a Fat Man bomb assembly being prepared for testing at the US Navy Saltwells ordinance facility near Inyokern, California (now China Lake Naval Weapons Center, near Ridgecrest, California).