Wednesday, October 23, 2013

Summer and fall galaxies

The long awaited fall transition to cooler and clearer weather has begun for my area. The skies are not only clearer and darker, the nights are longer and the bugs no longer lurk as massive swarms in the darkness to feast upon stargazers. Last week a night came along that made going to a darker site more than worthwhile, so drove out to the countryside with the 15-inch to observe objects along the summer Milky Way and to log previously never seen summer and fall galaxies and nebulae. When I wasn't observing from my usual darker site, I was observing deep sky objects from home when the moon was absent.
First among the objects I wanted to look over was the obscure but pleasing open cluster NGC-1027 in Cassiopeia. It was surprisingly apparent from home, so I sketched this one from the driveway. It's not one of the better know open clusters in Cassiopeia, but a nice object at 142X even though its stars were fairly scattered.
The summer constellation Lyra is not what many amateur astronomers regard as a region of the sky where one would find galaxies. However, a surprising number of them can be found in Lyra, NGC-6646 being among the brightest. Small, faint and round with a brighter center, this object has an apparent magnitude of about 13. Its small apparent size gives it enough surface brightness to show up in less than perfect skies through the 15-inch. This system is a Sa spiral resembling M-81 but face on and far more distant.
NGC-6745 is another Lyra galaxy known as the "Birdhead Galaxy" due to it's distorted and bizarre shape. It is in fact not a single galaxy at all, but three of them some 200 million light years away merging into a single, larger galaxy. Very small and faint, it responds well to high magnification. I found a 6.7mm Explore Scientific 82 degree eyepiece gave the best view at 298X, which enabled it to reveal itself amid the dense field stars of the Milky Way. Shining at 13th magnitude, it is in range of 10 or 12-inch telescopes from dark sites. I was surprised at how easy it was to find with my 15-inch from an area subject to considerable light pollution. To me it did look somewhat like a bird's head, or a scrawled letter L.
NGC-6871 is one of countless open clusters to be found in Cygnus. I have discovered though this large and scattered star cluster tends to hide in plain sight, until a photo showed where the central concentration is. Shining at a combined magnitude of 5.2 and spanning 20 arc-minutes, NGC-6871 is a fine object for small telescopes. As a bonus, there's numerous other open clusters and nebulae in the same area.
In addition to two Messier objects and two well known planetary nebulae, Aquarius is home to numerous galaxies. Most are faint but a few are bright enough for 8 or 10-inch telescopes from dark sites. NGC-7252 shines at  magnitude 11.7 and has a classification of SBO. It is also known as the Atoms for Peace Galaxy because of the filaments that extend from it in photos, resembling the international symbol for the atom. It has in fact recently merged with another galaxy. While I did not see the filaments, I did see a weak central core that is displaced to one side at 298X. Small and faint, it responds well to higher magnifications to bring it forth from the surrounding sky glow.
Yet another Aquarius galaxy is the type SBb barred spiral system NGC-7416. Shining at magnitude 12.4, this galaxy has a fairly high surface brightness due to it being nearly edge-on. I saw a distinct unevenness in it's brightness where the central bar and spiral arms were inside the rest of the disk. Like NGC-7252, this galaxy responds well to high magnifications.
NGC-7457 is one of a huge number of galaxies in reach of amateur telescopes in Pegasus, and one of the best. Shining at magnitude 11 with an oval disk some four arc-minutes long, this lenticular galaxy shows a very strong brightening towards the center. It is bright and relatively easy to locate, with little to no structure visible other than the increasing brightness towards the center and a bright nucleus.

Before clouds rolled in and I took the telescope down for the night, I stopped to look for the globular cluster G-1 in M-31, and took the time to look at the galaxy itself along with it's nearby neighbors M-32, M-33 and M-110. I did not see the globular cluster, but I did get a nice view of these galaxies along with other deep sky objects. I also managed to find the dim planetary nebula Abell 70. I am looking forward to this years Deep South Regional Stargaze, set to take place at the end of this month. I plan to bring the 15-inch there and pursue fainter objects I have not been able to find locally. I will be posting the sketches I make while at the DSRSG. The cooler fall weather will make sky conditions far better than they've been all summer long. It will be a nice short vacation for me.