The California Nebula (NGC 1499) is an emission nebula located in the constellation Perseus. It is so named because it appears to resemble the outline of the US State of California on long exposure photographs. It is almost 2.5° long on the sky and, because of its very low surface brightness, it is extremely difficult to observe visually. It can be observed with a Hα filter (isolates the Hα line at 656 nm) or Hβ filter (isolates the Hβ line at 486 nm) in a rich-field telescope under dark skies. It lies at a distance of about 1,000 light years from Earth.