I finished this a couple weeks ago but forgot to post it apparently
Sh2 is the Sharpless catalog, which is a catalog of over 300 hydrogen-emission regions from American astronomer Stewart Sharpless, published in 1959.
Sh2-188 is a planetary nebula in the constellation Cassiopeia. It's about 850 lightyears away, in our own galaxy.
Planetary nebulae are dying stars that aren't massive enough to go out with a supernova bang. Instead, as they run out of hydrogen to fuse, the core begins to collapse inward without the outward pressure of the energy from fusion, which heats the core. Cooler, outer layers of starstuff puff off out into space, driven by the stellar wind. The core becomes a white dwarf, no longer fusing, but still shining from the latent heat. The planetary nebula phase only lasts about 10-20,000 years or so -- very short in a star's billions of years of life! This is the fate of our own Sun; hopefully it will make a beautiful planetary nebula for some extraterrestrial astronomers to enjoy someday.
I actually started this target a year ago, but only got 6.5 hours of exposure time, which wasn't enough to make a nice image. This time, I started on it in September, and managed to get a grand total of 44 hours on it, but after eliminating some for having less-than-ideal stars, or poor atmospheric conditions, or ones that didn't want to align, I ended up with 31h25m total -- still a nice amount of total exposure time
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