Shot Encore was the tenth nuclear detonation of Operation Upshot-Knothole, dropped by a B-50 bomber on 8 May 1953 from an altitude of approximately 5,800 metres over Area 5 of the Nevada Proving Ground. The Mk-6D bomb detonated at 739 metres altitude — 5 metres west and 286 metres south of the designated ground zero — producing 27 kilotons against a predicted yield of 30–35 kt. It was a weapons effects test, the shot name Encore following the DOD convention of using abbreviation mnemonics: E for Effects. Total device weight was 3,779 kg. Operation Upshot-Knothole, of which Encore was part, released approximately 35,000 kilocuries of iodine-131 into the atmosphere — the most of any continental test series — producing civilian thyroid exposures projected to result in approximately 28,000 cases of thyroid cancer and 1,400 deaths.