Hello friends and welcome to the new edition of the TSS
Challenge. This month the primary plane of the Milky Way will be shifting a bit to the west and some of the autumn (or spring depending where you live) sky will begin to make its appearance. The night sky always gives us both a sense of comfortable familiarity and a sense of renewed expectation each month. We say goodbye to some old friends and hello to other old friends. That is one of the many great things about this hobby; we meet and make many good friends both down here and up there! So I wish you good luck and hope you enjoy the pursuit and results thereof.
Northern Celestial Hemisphere
Messier 15 / NGC 7078 (Pegasus, globular cluster, mag=6.3, size=18.0’, class=4):
As the winged horse begins its climb in the eastern sky, the bright star Enif (Epsilon Pegasi) marking its nose is often what we see first. Just over 4° northwest of the star one can easily scoop up this fine globular cluster. The bright field star HD 204862 (mag 6.1) lies in tight proximity to the cluster, only about 17’ to its east. The cluster is smaller than the showpiece M13 in Hercules, but it is still intensely bright in the eyepiece. It is easily seen in binoculars and even magnified finders. In dark skies it may even be glimpsed with the naked eye. It sports a very bright and very tight core, which does not give up any resolution. However, its outer fringes and inward toward the core can be resolved with enough aperture
This beauty was discovered in 1746 by Jean-Dominique Maraldi while tracking Comet de Cheseaux of 1746. Interestingly the cluster has undergone core compression whereby many of its stars have been pulled inward, giving it one of the most densely packed cores of the Milky Way globulars. An interesting aside to this globular is the fact that it contains a planetary nebula, known as Pease 1 or more officially as PK 065-27.1. It has an apparent magnitude of around 15.5 and a miniscule diameter of around 3.0”. This object is an extreme challenge for those with larger aperture
and darker skies, and requires very precise image based finder charts to locate with certainty.
NGC 7243 (Lacerta, open cluster, mag=6.4, size=30.0’, class=IV2p):
The constellation representing the celestial lizard is frequently ignored by many observers. While it is true that it does not contain any Messier
objects, that does not mean it is void of observable DSOs
. This cluster was discovered by William Herschel in 1788. In his notes he described it as "an extended cluster of coarsely scattered vL (i.e., bright) stars, in the direction of the parallel nearly; about 16' long." Its large field is indeed scattered and coarse, but it still is a curiously pretty cluster. There are enough stars strewn across its field that intrigue the eye with numerous sub-patterns and geometric shapes. Give this object a try and see if you enjoy it as much as I do.
NGC 7331 (Pegasus, spiral galaxy, mag=9.5, size=10.2’x4.2’, SBr=13.3):
This bright and beautiful spiral was discovered by William Herschel in 1784, when he noted it as “pB, cL, E, lbM” (i.e., pretty bright, considerably large, extended, little brighter in the middle). Located in northwestern Pegasus, just over 1° south of its border with Lacerta and just under 4.5° NNW of the double star Eta Pegasi (mag 2.95 and 9.87), this is truly a fine galaxy for both visual and imaging. Not particularly difficult from areas of moderate light pollution, it truly shines in dark skies as do all diffuse and extended objects. It sports a very bright core set within its tilted oval disk. Viewing dark lanes and mottling within the disk is also possible.
7331 is the dominant galaxy in a small unrelated grouping of galaxies known as the Deerlick Group. They are also affectionately known as the “dog and its fleas.” The dog (NGC
7331) is a foreground object, while its fleas on its back (immediately east of the “dog” are more distant galaxies physically unrelated to one another that form a line of sight grouping. The four smaller galaxies are NGC
7335 at mag 13.3, NGC
7336 at mag 14.5, NGC
7337 at mag 14.4 and NGC
7340 at mag 13.7. If you have medium to large aperture
and have decent skies, see how many of the little itchy critters you can pick up. This group makes a fine imaging target as well, presenting an interesting contrast of large and bright with small and dim.
Southern Celestial Hemisphere
Melotte 227 (Octans, open cluster, mag=5.3, size=50.0’, class=II 2 p
Discovered by Philibert Jacques Melotte around 1915, this very deep southern object was deemed an open cluster initially. However, some studies have concluded it is merely a non-related line of sight asterism
. Also known as Collider 411, regardless of whether it is a true cluster or random happenstance of stars, it is a curious and obvious object. Totaling about 40 stars, it is best observed using lower magnification due to its large angular size of around 50 arc minutes. At -79° declination, it is indeed a deep southern object. However, if it graces your sky, turn a scope its way to see how many stars you can pick out.
NGC 6818 (Sagittarius, planetary nebula, mag=9.3, size=0.45’x0.4’, SBr=7.2):
Nicknamed “The Little Gem
” this bright planetary is located less than 2.5° south of the Sagittarius-Aquila border and just over 41’ NNW of our third southern challenge object, NGC
6822. First observed by William Herschel in 1767, he wrote the following description of this marvelous object: "a small beautiful planetary nebula, but considerably hazy upon the edges; it is of uniform light throughout, considerably bright. Perfectly round, 10 or 15" in diameter. My brother Jacob being in the gallery, I showed it to him." In my experience with the object, I found it slightly of our round, with an obvious pale blue color. Like Herschel, I find its edges soft, but unlike him, I find the light across the disk not totally uniform, with its eastern side being brighter. I invite you to observe and/or image this object to see how your impressions compare.
NGC 6822 (Sagittarius, barred irregular galaxy, mag=8.8, size=15.5’x13.5’, SBr=14.5):
Discovered in 1884 by E.E. Barnard, he initially considered it a variable nebula. Barnard studied this galaxy extensively over the years and published his work "NGC
6822, A Remote Stellar System" in 1925. Additionally, it is affectionately known as “Barnard’s Galaxy.” It also carries a duplicate identifier in the Index Catalogue, IC
1308 due to some identification errors by later observers. This barred irregular galaxy is a member of the Local Group of galaxies, and lies about 1.63 million light years distant. It is a challenging object visually because of its extended angular size and resulting low surface brightness. Seen from a darker area, it can appear as a diaphanous brightening against the sky. With some aperture
and study, one may detect some of its brighter HII regions as well. In images it is a beautifully delicate visual entity that tickles the imagination, and makes a very curious study.
There you have it for this month. I hope you will add these objects to your regular plans observing and imaging plans, even if you’ve visited them previously. They are all well worth additional looks with a fresh sense of curiosity and wonder. Good luck and keep looking up there, you just might surprise yourself as to what you can see.