This is been a long cloudy winter so far, not a single clear night since a spurt I had at the beginning of November. I decided to just go ahead and start processing what I have. I was working on three targets at once, beginning with taking data on NGC 281 before the Horsehead nebula would rise, when the telescope would switch over to that.
NGC 281, the Pacman Nebula, is a bright H II emission region in Cassiopeia. It’s about half a degree in apparent size, the same as the Moon, and at 9,500 light years away, that makes it about 50 light years wide, or wide enough to fit 40,000 Solar systems. When the light that hit my telescope left these ionized atoms, the last ice age was just ending.
Over five nights, I collected about 19 hours of data, which is not a quantity I am normally satisfied with, but I believe was enough for this bright target. This is also my first test of RC Astro’s new BlurXTerminator, a neural network-driven deconvolution tool. Deconvolution is an ill-posed problem that is very difficult to execute exactly, and something to assist the sharpening of an image is immensely useful to me since my big scope is just a bit oversampled for my skies. I stretched and processed the stars and the nebula separately, which really lets me tame dense star fields while keeping the stars’ color. This was one of the first nebula I did when I got the tracking platform for my Dobsonian way back, and I think I did it justice this time.
In the background, we have a few distant galaxies visible,
I found some redshift data for these on SIMBAD and calculated flat comoving radial distances for them,
| PGC | z | Comoving radial distance (Mly) |
| 137297 | 0.04670 | 649 |
| 137305 | 0.03236 | 451 |
| 137314 | 0.08400 | 1,158 |
The light from little PGC 137314 took off 1.15 billion years ago, when a 1km wide asteroid crashed into Scotland, and multicellular organisms were starting to evolve!
