Dutch physicist Willem Hendrik Keesom (1876-1956) specialized in cryogenics. In 1926 he became the first to solidify helium, and among his discoveries are He I and He II. In 1932 he achieved the temperature of -272° C, only one degree above absolute zero. The name was suggested by W. A. Fröger.
Discovered on 24-9-1960 in Palomar by van Houten, C. J., van Houten-Groeneveld, I., Gehrels, T.