IC 2162 (2-11-2011) (with a defect)

This nebula in the constellation Orion is one of those places in our galaxy where stars are forming from gas and dust clouds. Energy from those young stars is caught up by gas molecules in the clouds and then is released in the form of light. The gas around the stars literally glows. Much of the gas is hydrogen.

Light at a wavelength of 656.28 nm is emitted by a hydrogen atom when the electron in the atom moves from one energy level (the third) down one (to the second). This kind of radiation is called H-alpha. What we call an H-alpha filter is a piece of glass with coatings on it that let just a few wavelengths of light through. In daylight, the filter looks like a mirror. The swath of spectrum the H-alpha filter lets through is just a few nanometers wide and is centered on the 656.28nm wavelength, to the exclusion of all others. Nearly all light pollution is excluded, as a result. So the filter allows one to take fairly detailed images of objects deep in space even from suburban backyards. This image is 12x10' through the 10" newt, Baader MPCC, and 12nm Astronomik H-alpha filter, with the Atik 16.

After looking at this image for some time, and examining others' images of this object, I've concluded that the red on the right side of the image is spurious, a system artifact. The off-axis guider had loosened slightly, so that side of the camera was slightly further away from the primary mirror than the rest of the system. The effect was to introduce noise in that half of the image. I have noticed this also in another image I took later that session. I may be able to extract the noise through processing, but I haven't had time to work on it yet. I'm keeping the image up, either way, but please note that fact.