The last couple of nights I’ve worked on imaging a region of the constellation Cygnus, called the North American Nebula. This region is actually a combination of “emission nebula” (the pinkish-colored Hydrogen Alpha that emits light directly), and “dark nebula” which is black-bodied dust that absorbs energy and blocks light. Cygnus is on top of the Milky Way, more specifically one of it’s arms, a little farther than midway out from the galactic core. It’s a star-rich region, and the dark nebula is actually part of a large dust lane. Dust lanes are large regions of dust and other particulate that generally stretch the length of each galactic arm in a galaxy.
This particular image is of the “eastern half” of “north america” in the nebula. The nebula get’s it’s name due to the way the nebula is shaped by the dark dust lanes that cross over it, which generally has the shape of the United States. Near the bottom right, where the nebula billows up, you have Mexico. The dark dust next to that forms the Gulf of Mexico, and the rest of the continent should be easily recognizable from there. Behind the dust is a very large region of hydrogen alpha, an HII region as they are officially termed. This is all the reddish-pink nebulosity, a molecular cloud spanning many hundreds or thousands of light years.. Along the lower edge and a spot along the left edge some more interesting gaseous formations can be seen in the nebula.
This image was created with my humble Canon 7D, and my wonderful 600mm f/4 L II lens. The lens, which was originally purchased for use as a wildlife and bird photography lens, has doubled very nicely as a powerful and fast (wide aperture/small f-ratio) telescope. This image was produced by stacking 49 out of 52 light frames, which were calibrated with 67 dark frames, 180 bias frames, and 30 flat frames. These “calibration frames” help remove camera sensor and electronics noise like hot and cold pixels, sensor bias (a fixed pattern effectively “baked” into the hardware structure of the sensor and the way the electronics feed electricity to each row, column, and pixel), and help remove lens vignetting (shading in the corners caused by the design of the lens itself) and dust spots (darker blotches caused by dust on the sensor, or possibly a filter in front of the sensor). The final calibrated integration results from a total of 3h 40m of exposure time, out of a total of 4h exposure time in the field. Image was processed with Adobe Photoshop and Astronomy Tools actions.