The California Nebula (NGC 1499/Sh2-220) is an emission nebula located in the constellation Perseus.
Its name comes from its resemblance to the outline of the US State of California in long exposure photographs.
The brighter section is almost 2.5° long on the sky and, because of its very low surface brightness, it is extremely difficult to observe visually.
But Photographically it shows up very well in long exposures. In this image I also captured the fainter section near the bottom of the frame showing
it actually covers more than 5 degrees of sky. It lies at a distance of about 1,000 light years from Earth.

The California Nebula fluorescence is due to excitation of the Hβ(486nm) line in the nebula by the nearby energetic(Blue star in the lower right of the nebula) O7 star,
Xi Persei (also known as Menkib). It looks fantastic in the H-alpha(656nm) wavelength as well.

Capture with a Samyang 135mm F2 lens, Bisque MyT mount, ZWO 294mc Cooled Cmos Camera, L-enhance filter,
ASI Air Plus via Wi-Fi to my I-pad, 30 x 2 minute subs, 60 minute total exposure integration time.
From my backyard observatory(bortle8) in Dayton Ohio.

Best Regards,

John Chumack