NGC 2440
NGC 2440 is a planetary nebula, one of many in our galaxy. Its central star, HD 62166, is possibly the hottest known white dwarf, about 400,000°F. The nebula is situated in the constellation Puppis.
It was discovered by William Herschel on March 4, 1790. He described it as "a beautiful planetary nebula of a considerable degree of brightness, not very well defined." The nebula is located about 1.23 kiloparsecs or about 4,000 light years from the Sun.