It’s been a while since I shared any astrophotography, besides the moon. As such, I have kind of been looking forward to this blog entry, as I’ve been collecting imagery for it for quite some time. I spent most of the summer working on a major summer constellation: Cygnus. Cygnus, or “The Swan” as it is in the original Latinized Greek, is one of the most prominent constellations during summer. It is probably more commonly known as the Northern Cross, or just The Cross, given that part of the constellation, an “asterism” as they are called (much like The Big Dipper is an asterism of the constellation Ursa Major), looks like a big cross. The primary named stars of the constellation are Deneb, the brightest at the tail, Sadr at it’s heart, Gienah on a wing, and Albireo at the head. There are a total of ten primary stars that make up the full shape of the swan and it’s wings, as well as countless other stars, emission nebula, dust lanes and dark nebula, reflection nebula, star clusters and more in the region.
The region itself is part of the Milky Way, our home galaxy. Cygnus sits about half way between the core of our galaxy, which from the northern hemisphere sits directly in the southern sky during the summer months, and the outer reaches of our arm of the galaxy, which stretches through Cassiopeia, Perseus, and a few other constellations near the north pole. While not as bright as the galactic core, as it does not represent nearly the same star density, Cygnus is home to one of our large, rich hydrogen regions. Large expanses of hydrogen emission nebula, long stretches of dust, star clusters and amazing planetary nebula and supernova remnants stretch all throughout the arms of our galaxy. While within the city, polluted by ever increasing amounts of light (light pollution, as it reflects off of atmospheric particular), the great expanse and beauty of Cygnus can not be recognized, if you are lucky enough to live under dark, rural skies away from the expanses of city or suburban life, you may have the opportunity to see the more than just the stars within Cygnus…you may be able to glimps the faint beginnings of some of the amazing regions I’ll be sharing with you here.
At my altitude (latitude), the heart of Cygnus, the region of molecular clouds around the star Sadr, passes directly overhead. This point is called the Zenithal Point, or just the Zenith for short. The Zenith is the best spot to image the sky, as the atmosphere is thinnest there (line of sight…look strait up, you look through less atmosphere in total than if you look towards a horizon.) Throughout the summer, starting in May and ending only just a week ago in August, I managed to create images of four major regions within Cygnus, most of them within the large molecular cloud that fills most of the region.
North America and Pelican Nebulas
The first region I’ve shared today is the North American and Pelican nebula region. This region is probably the most recognizable of the nebula in Cygnus. Separated by a dark nebula, a long, thick, nearly pitch black stretch of dust, North America nebula is to the left.
The large pinkish region resembles the continental United States, with part of the dark nebula forming the “Gulf of Mexico” near the lower center of the image. The gulf can be seen here:
The “Gulf of California” region that separates Baja from Mexico, is an interesting nebulous region called The Great Wall. A larger version of that region can be seen here:
To the right of the dark lane next to North American nebula is Pelican nebula. It usually takes a moment to recognize the shape out of the darker reddish nebula here, however the interesting nebulous structure imaged below forms the pelicans body.
Once you know that, you should be able to pick out it’s head and bill in the close up image below:
The Sadr Region – Butterfly and M29
The second region I’ve shared today is what we call the Sadr region. This region surrounds the second major star in Cygnus, the star at the center of the swan. A rather vast expanse, it has a cracked and broken appearance due to the presence of numerous dark dust lanes that spider through the hydrogen emission nebula. This region is packed with interesting objects, a number of small reflection nebula, interesting and complex dark nebula structures, and a large region called Butterfly Nebula. The bright star near the center is Sadr itself, who’s own light reflects off a bit of the nebula nearby (faintly visible to the lower right behind the star). To the left of Sadr a short ways is a small open star cluster, NGC6910:
To the right and slightly lower closer to the right edge is another open cluster, one of the Messier objects, M29:
The Butterfly Nebula is the region just below Sadr, near the center of the image. It’s wings are bisected by the large dust lane that passes through it. In this particular frame, the lower ring and head of the butterfly are cut off, but the general shape can still be seen:
Within the large dust nebula some stars are partially obscured, resulting in a reflection nebula:
Small reflection nebula are common in regions like this, where stars are actually shrouded within the dust. This region is packed with interesting dust structures, obscuring the background light from the Cygnus molecular cloud and more distant stars…that light itself revealing the intricacies of the dust lanes and structures:
This region was one of the first I imaged. At the time, my skill was considerably less than it is now, and that shows in the overall results. In the future I have ambitions to create large mosaics of entire regions of the sky, such as the Cygnus and Orion molecular clouds. I hope to have even more advanced equipment sometime early next year, which should make it possible to resolve considerably more detail with less noise and “grit”.
The third region of Cygnus that I am sharing today is the region around Crescent Nebula. Crescent is very close to the Sadr region…not far out of the frame to the right. The bright hydrogen emission nebula extend well beyond the area framed in the Sadr region above, extending to Crescent nebula and much farther. That background nebula is dimmer in those areas, requiring much deeper exposures to reveal. Crescent Nebula is a challenging object to image, first because of the dimness of the background nebula, but second because the Crescent itself is a highly complex, multi-layared, very structured object:
The primary structure of Crescent, as I’ve imaged here, is primarily intense hydrogen emission nebula, emitting a lot of light in the Ha, or Hydrogen-Alpha band. Surrounding, and partially intertwined with, this hydrogen emission nebula is also an oxygen emission nebula, that emits primarily in the OIII or Oxygen-3 band. The oxygen part of Crescent is much fainter, and any light for it is usually obliterated when imaging within the city (as I do). Despite the challenges, if you examine the above crop closely, you can very faintly see a grayish-blue shell around the brighter red structures of Crescent.
It took the bulk of the summer to gather the necessary data to render this image properly. I was regularly plagued by weather, which prevented my ability to image at all throughout most of the core summer months. When I did have a chance at a clear sky, I ran into several issues with my mount that reduced the amount of time I effectively had to image this region even further. In the end, I was able to get enough data to render both the Crescent itself, as well as a fair amount of the background emission nebula. Needless to say, imaging crescent in significantly more detail, with narrow band filters for the Ha and OIII bands, is a top goal once I acquire more sensitive and capable camera equipment, and a larger telescope.
The Veil Nebula
The final region I am sharing today is the Veil Nebula. Veil, while still a part of Cygnus, is somewhat separated from the greater expanse of the Cygnus molecular cloud. It is below North American and Pelican nebulas a short ways, off on it’s own without any significant background nebula and fewer stars (although relative to some regions of the sky, still a SIGNIFICANT number of stars.) Veil is a very complex, multi-faceted, highly structured object. It emits light in both hydrogen and oxygen bands, as can be seen by the red and blue filaments. It is thought to be the remnant of a supernova, however it may simply be a unique structure in the universe (especially given it’s size, which is quite immense.)
Complex objects like Veil Nebula are often broken down into smaller regions. The veil naturally breaks down into three major regions: Eastern Veil, Western Veil, and Pickering’s Triangle in the center. Pickerings Triangle is pictured above. Western veil is also known as The Witches Broom, for it’s broom-like shape:
Eastern Veil is a bit more separated from the other two parts, however it is highly structured itself, almost like writhing blue and ref flame twisting about itself:
Personally, I think Veil nebula is one of the more amazing objects in the night summer night sky. It’s extensive, yet delicate and almost lace-like structures are both stunningly beautiful and incredibly intriguing. The depth of detail in this one area of space is extreme, and one could spend an entire summer doing nothing but imaging the various different parts of it’s vast structure. More to look forward to in the future, especially once I acquire some imaging equipment that will allow me to do narrow band exposures, which will allow much deeper, more detailed imaging even under my heavily light polluted skies.
While that is all I have for today, it’s not the last of my astrophotography for the summer. I imaged other objects, some of which I have just about completed, some of which still need more exposure. The summer sky is beginning to wane, and within a month the winter constellations will be above the horizon before twilight. It feels a little strange. I’ve only been doing astrophotography for six months, almost exactly (couple weeks longer), and I started with the same constellations that I now see rising in the early morning as I pack up my imaging gear. The first regions of the sky that I imaged were in Orion…the Orion and Horse Head nebulas. Even before picking up my astrophotography equipment, I had started trying to image Orion and Running Man nebulas with the standard photography equipment I had (no tracking) about this time last year. So in a sense, it has been one full year since I first got serious about astrophotography.
Back then, I truly had no idea what I was doing. This time, I’ll be going into fall and winter from the get-go with significantly more skill. Hopefully I’ll be able to capture more detail on Orion and Horse Head nebulas, as well as get some quality clear, dark sky time on some of the other interesting structure within Orion, Monoceros, Gemini, Pleiades, and the other winter constellations. So, stay tuned. Lots more to come!