The California Nebula (NGC 1499) is an emission nebula located in the constellation Perseus. It is quite weak, and for visual observation requires dark skies and an H-beta filter. For astrophotography it is an ideal objective, both in narrow band and continuous. It is about 1500 light-years away, and it is very extensive, since its size in the sky is about 4º (105 light-years) x 1º. In that region there are many dark nebulae, so it is believed that NGC could be part of one of them, although ionized by the star Xi Persei, visual magnitude 4.04 (Menkib). This star is enormously hot, and emits a strong stellar wind, 10 million times more intense than that of our Sun. It produces a small reflection region (bluish), and itself ionizes the nebula (reddish). Most emission nebulae are illuminated by stars formed within the nebula itself, but Menkib is a runaway star, originating in the Perseus OB2 stellar association and thrown toward NGC 1499 by interaction with a massive star or a stellar explosion. Your encounter with NGC 1499 is chance.

After some failures capturing wide fields, I adapted a Samyang 135 lens to an ASI 1600MM camera, adding a filter case. The California was ideal for the experiment, since I wanted to capture it in its entirety and in narrow band. The backfocus had to be adjusted a lot, and in the end it was clear to me that to get decent stars I had to close down to f/4 and not be ambitious. I still had calibration issues with the short shots, so 8+ hours of RGB shots only worked for the stars. The narrow band shots total 18 h 49 m.The photograph is composed with a SHO palette and RGB stars. Menkab is the bright star located in the center right. The structure of the nebula is filamentous, and shows several ionization fronts. Dark spots produced by intervening dust clouds are observed. The surrounding dust and gas appear as faint nebulosities. The field of view is 7º 19' 56.7" x 5º 26' 56.3"