The California Nebula lies in the constellation Perseus, approximately 1,000–1,500 light-years away from Earth. Spanning nearly 2.5 degrees across the sky—about five times the apparent diameter of the Moon—this vast nebula is an impressive yet challenging target for visual observation. Its low surface brightness makes it difficult to spot without the right equipment; observers typically need a rich-field telescope, dark skies, and a nebula filter to glimpse it properly.
Also known as NGC 1499 and Sh2-220, the California Nebula was discovered by Edward Emerson Barnard on November 3, 1885. It resides within the Orion Arm of our Milky Way Galaxy, the same spiral arm that contains our Solar System. The nebula lies along the edge of the Perseus OB2 association, a stellar grouping rich in young, hot stars.
The California Nebula is a classic emission nebula, meaning its glow originates from ionized gas. Atoms within the nebula recombine with free electrons that were stripped away by intense ultraviolet radiation from nearby stars. The primary ionization source is believed to be Menkib (ξ Persei), a bright and massive O-type star.
Interestingly, Menkib was born about 400,000 years ago within the Perseus OB2 association but only encountered the nebula around 100,000 years ago. While Menkib itself lies just outside of this image, slightly below the lower border—you can see its position in a wide-field image of the California Nebula here:
Dust in California (NGC 1499) – Astrojolo.com
I have captured the narrowband data for this image over a few February nights with the Moon present, but at some point, I just said it is enough. The most problematic element appeared to be the oxygen due to two facts. First, there is a very small amount of oxygen in the California Nebula. Second, the Moonlight affects the light in these wavelengths very much, especially when all I have is an old 8nm wide filter. But the final outcome is decent, full of colors, maybe too much, but I decided not to process it further, or again, reprocessing is not any fun for me 🙂
Image technical data: Date: February 2025 Location: Nieborowice, Poland Telescope: TS Photoline 130/910 Corrector: TS FF/FR 0.8x Camera: QHY268M Mount: EQ6 Guiding: ASI290MM + Evoguide ED50 Exposures: HSORGB 320:300:300:90:90:90 minutes Conditions: Bortle 6, transparency and seeing medium-good, partially Moon and high clouds
