DETAILS
Exposure: 20×480″ @ ISO 1600
Telescope: William Optics Megrez 88FD with Baader MPCC
Filter: Baader H-alpha 7nm 2″
Mount: Meade LXD-75 Autostar
Camera: Modded Canon 350D
Date: 9th Novemberber 2008
Location: Cabrera de Mar (suburban site) (Barcelona)
Comments: This was my first H-alpha image, the focusing was very difficult because I did it by hand and did not have a mask or other focusing aid.

The California Nebula, also known as NGC1499, is an emission nebula in constellation Persus, about 1500 light-years away from the Earth, an it’s about 100 light-years long lying within the Milky Way’s Orion Arm, like our Sün.
This nebula not only glows strongly due to H-alpha emission but also H-beta. The emission of photons by the Hydrogen atoms in this gas are caused by the elevation and subsequent drop in energy level of electrons. The electrons gain energy by collision and (most importantly in this case) by interacting with energetic photons coming from Zeta Persei, the bright star at the bottom right side of the image.