The Mark 39 nuclear bomb and W39 nuclear warhead were versions of an American thermonuclear weapon, which were in service from 1957 to 1966.
The Mark 39 design was a thermonuclear bomb (see Teller-Ulam design) and had a yield of 3.8 megatons. The design is an improved Mark 15 nuclear bomb design (the TX-15-X3 design and Mark 39 Mod 0 were the same design). The Mark 15 was the first lightweight US thermonuclear bomb.
The W39 warhead is 35 inches in diameter and 106 inches long, with a weight of 6,230 to 6,400 pounds. It was used on the SM-62 Snark missile, Redstone IRBM missile, and in the B-58 Hustler weapons pod.
The B39 bomb is 35 inches diameter and 140 inches long, with a weight of 6,650 to 6,750 pounds, and was carried by a number of aircraft.