Tonight is the waning of the first of autumn’s Harvest Moons. Targeting anything in a full moon’s neighboring radiance is always more challenging. However, in my quest to search out new galaxies far, far away, I thought I’d give Abell 347, a cluster of faint galaxies, which includes NGC 912, a try. All of this group are in the constellation Andromeda. Abell 347 is rather more difficult to image, since all of its galaxies are 13th magnitude or greater.
The Abell catalog is devoted to galaxy clusters. First assembled by UCLA astronomer George Abell in 1958, it is currently an almost complete list of approximately 4,000 galaxy clusters.
I decided to bin at 2 X 2 with 30 one-minute exposures. I have been doing some reading online about the advisability of 2 X 2 binning with a one-shot color CCD and, while there are trade-offs that I explained before, it is a faster way to go deeper.
Below is my image of Abell 347, with circles around 10 of the more prominent galaxies in the group. To quote astronomer Jim Shields: “Observing galaxy clusters is a way of looking directly into the unimaginable depths of space. Whether one finds this terrifying or not depends, I suppose, upon one’s taste and temperament. Personally I find the experience exhilarating, rather like the bracing air and vast panorama from the top of a high mountain peak.”
Click on for a closer view.
Abell 347 is quite close to NGC 891. I thought I might be able to grab both images in one picture, but no luck. Below is a picture of this edge-on spiral galaxy I took several years ago.
Another DSO I had never imaged is in the constellation Sagitta (the Arrow). IC 4997 is a planetary nebula. The image is binned at 2 X 2 for 20 one minute exposures.
IC 4997 is one of several “stellar” planetary nebulae that to the eye are physically so small or so far away (or both) that they just look like stars.
Small as it is, the great resolving power of the Hubble reveals an intricate bi-lobed structure seemingly overwhelmed by a relatively brilliant 14th magnitude central star. IC 4997 is clearly a nebula to keep our eye on, as it is telling us something about how these marvelous objects are born and develop in their youth. Below is Hubble’s image.