A plutonium atomic bomb (nicknamed “Fatman”) dropped by the American B29 bomber “Bockscar” exploded in the air about 500 meters over this site at 11:02 a.m., August 9, 1945, causing approximately 150,000 deaths or injuries.

Then I look up at the sky over Nagasaki, about 500 meters in the air.

Reference

Japanese https://note.com/yasuharunagura/n/n39f5ea9146d1