A while ago, I posted a monochrome image (H-alpha channel) of M16 and another bright, but unknown (to me) hydrogen region. The second object did not appear in my planetarium software and very few images I could find on the internet included it, so I asked people for help in identifying it. I eventually came up with an answer myself: It was Sh2-54, AKA Sharpless 54. More importantly, this led me to the online catalog of Sharpless objects, http://www.sharplesscatalog.com/.
Stewart Sharpless was an American astronomer who worked on a number of important projects and with some well known astronomers, including Edwin Hubble. He spent much of his career working for the U.S. Naval Observatory in Flagstaff, where he surveyed and cataloged HII regions. His first catalog of 142 such objects, Sh1, was published in 1953, and the second edition, Sh2, containing 313 objects, in 1959.
Many of the Sharpless objects are well know, and included in other catalogs. But for the narrowband astrophotographer, such as myself, the Sh2 catalog is a treasure trove of potential targets and many of them are not to be found in any of the more commonly used catalogs.
Sh2-157 is the large, complex region in the upper right of this wide-field image. The much better known Bubble Nebula is in the lower left, and NGC7538 is the small, bright nebula in the upper left. Also included is a pair of open star clusters; M52 in the lower left, and NGC7510 in the top center.
I captured this image over the last 3 nights and liked it so much that I had to process and post it right away, but I do have a number of other images in the works as well, including the final (color) version of M16/Sh2-54, and some more images from the recent star party.