CP Puppis (or Nova Puppis 1942) was a bright nova occurring in the constellation Puppis in 1942. From a 17th magnitude star, it reached an apparent visual magnitude of –0.2 then began a rapid decline. It had dropped by three magnitudes in an interval of 6.5 days, one of the sharpest declines ever noted for a nova. About 14 years later, the shell ejected by the nova event was detected, which allowed the distance to be computed. In 2000, this distance was revised to 3,720 light-years (1,140 parsecs) after correcting for probable errors.