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 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. Its fluorescence is due to excitation of the Hβ line in the nebula by the nearby prodigiously energetic O7 star, xi Persei also known as Menkib, seen at center and to the right (Wikipedia).
HaRGB composition, total integration 5.7hrs, December 2014. Takahashi FSQ85 EDX at F3.9 - Avalon Linear Fast Reverse - Atik 383L+ - Baader LRGB & Astrodon NB 5nm filters.
NGC1499The California Nebula