TSS Bi-monthly DSO Challenge for September/October 2023

[kt4hx]

Here we are with new skies and some new objects for you to add to your normal observing, sketching and/or imaging plans. As the months pass, our sky rotates bringing interesting objects into view. This constant change keeps things fresh and interesting, giving us an endless source of deep sky objects to pursue. This constant change also invites and challenges us to pursue our love of the night sky.

For this bi-monthly challenge, we northerners will take a peek into Cassiopeia, Lacerta and Cygnus. Our friends south of the equator will get to visit Octans, Aquarius, Sculptor and Grus. All these highlighted constellations of course contain far more treasure than we can cover here in any single issue. Certainly all are worthy of your attention beyond what is contained in this challenge. So once you are in each constellation, I encourage you to look around to see just what can be found.

So let’s delve into the objects for September and October. Be sure to check the list for the opposite celestial hemisphere. Depending upon your latitude, you just might be able to pick up something in the list that lies beyond the celestial equator. Good luck and as always, have fun. Please report your results so that we can all share in them and learn together.


Northern Celestial Hemisphere:

IC 1590 (Cassiopeia, open cluster, mag=7.4, size=4.0), type=III1m:
NGC 281 (Cassiopeia, bright nebula, mag=??, size=35.0’ x 30.0’):
This open cluster and emission nebula are a two for one deal. The cluster, IC 1590, is embedded in the heart of NGC 281 and is the primary energizer of the nebula. The duo are located about 1° 41’ due east of the bright star, mag 2.2 Alpha Cassiopeiae (Shedir). The cluster is a tight grouping at the center of its progenitor nebula, and is dominated by the quadruple star ADS 719, with the A through D components ranging from mag 7.8 to 9.7. With careful study one can see the small cluster swaddled in the misty hazy of the nebula, which is sometimes called the Pac Man Nebula based on its appearance in deep images. Some sources mistakenly list the nebula and cluster under the single identifier of NGC 281, but that is incorrect, as each has its own place in the NGC/IC Catalogue. Use of a narrow-band nebula filter, such as the DGM NPB or Orion Ultra Block can help with picking up the nebula visually by boosting its contrast. The pair is a fine target for imagers, providing a nice contrast between the two parts of the whole. Turn your scopes their way and see what you can make of this interesting combination.

Historically, the nebula NGC 281 was discovered by Edward Bernard in 1881, and possibly re-observed by Barnard in the 1890’s and unfortunately given a second identifier of IC 11. Credit for the embedded cluster, IC 1599, goes to Guillaume Bigourdan who was the first to bring it to our attention in 1899.


NGC 7209 (Lacerta, open cluster, mag=7.7, size=25.0’, class=III1p):
This nice open cluster is located in the celestial lizard, just inside its border from Cygnus. A William Herschel discovery in 1788, he described it as "a large cluster of pretty compressed considerable large [i.e. bright] stars, above 15' diameter."

The cluster offers a rich grouping of stars in an overall generally rich stellar field. Depending on conditions and aperture it is possible to see upwards of 30 to 40 stars scattered over its angular dimension, with numerous pairs and curves of stars being seen. Lacerta is an often overlooked constellation between Cygnus and Andromeda. But it does contain some nice open clusters and other types of DSOs to challenge the observer/imager, and this is a fine example.


NGC 6826 (Cygnus, planetary nebula, mag=8.8, size=27.0” x 24.0”, SBr=7.4):
The famous “blinking planetary” is located just under 1.5° ENE of mag 4.5 Theta Cygni. This object was discovered in 1793 by William Herschel. He described it in detail thusly - "a beautiful phenomenon. A bright point, little extended, like two points close to one another; as bright as a star of the 8-9 magnitude surrounded by a very bright milky nebulosity suddenly terminated, having the appearance of a planetary nebula with a lucid center. The border, however, is not very well defined. It is perfectly round and I suppose about 1/2' in diameter. It is of a middle species between the planetary nebula and nebulous stars."

The curious blinking effect that gave it the nickname is because of the bright central star of mag 10.4. When viewed with direct vision, the central star dominates the nebula’s disk, but with averted vision, the nebula takes prominence over the central star. However, with larger aperture, the increased brightness of the nebula’s disk mitigates this blinking appearance. Like most planetary nebulae, it responds well to an O-III line filter. In larger apertures some unevenness within its disk may become apparent, and one may glimpse some annular structure as well.


NGC 6946 (Cygnus, spiral galaxy, mag=8.8, size=11.5’x9.8’, SBr=13.8):
This face-on barred spiral straddles the Cepheus-Cygnus border. However, its center point lies just inside Cygnus, so that is where it calls home against the night sky. Famously known as the Fireworks Galaxy because it has experienced 10 observed supernovae over the past century, it was discovered by William Herschel in 1798. In his notes he described is as "considerably faint, very large, irregular figure, a sort of bright nucleus middle. The nebulosity extends 6 or 7'. The north seems to consist of some very small [i.e. dim] stars; the nebulosity is of the milky kind. It is a pretty object." It also appears in the Arp Catalogue of Peculiar Galaxies as Arp 29 being an example of a galaxy with one heavy arm.

Similar to most face-on oriented and large angularly sized galaxies, it appears fainter due to lower surface brightness. This object also lies near the primary Milky Way plane, thus it also suffers some obscuration by galactic dust within our galaxy. It presents delicate spiral structure, and lies between a spiral and barred spiral in morphology, with a small weak central bar. For many observers it will only appear as a thick oval diffuse ghostly glow in a fairly rich star field. But with more aperture and darker skies, its diaphanous spiral structure can be glimpsed.


Southern Celestial Hemisphere:

Melotte 227 (Octans, open cluster, mag=5.3, size=50.0’, class=II2p
Discovered by Philibert Jacques Melotte around 1915, this very deep southern object was looked upon as an open cluster initially. However, some studies have concluded it is merely a non-related line of sight asterism, though some sources still plot and list it as a cluster. Also known as Collider 411, it is located just over 4.5° southwest of magnitude 3.7 Nu Octantis. It is best viewed with lower magnification and a wider field. While the large field contains about 40 stars, one should be able to discern upwards of 15 members of magnitude 10 and brighter. At -79° declination, it is indeed a deep southern object. However, if it graces your sky, try pointing a smaller aperture wide field scope or even binoculars its way to see how many stars you can pick out.


NGC 7009 (Aquarius, planetary nebula, mag=8.0, size=34.8”, SBr=6.6):
One of the glorious objects below the celestial equator is the famous Saturn Nebula, located not quite 1.5° west of mag 4.5 Nu Aquarii. Discovered by William Herschel in 1787, he described it as "considerably bright, strong nebulosity of an irregular square figure.” The curious nickname, attributed to Lord Rosse, comes from the stubby extensions (ansae) that can sometimes be seen protruding from both sides of the slightly oval disk. This feature gives the vague illusory effect of edge-on rings.

Somewhat large for a planetary, its bright disk often appears as pale blue in color. With larger aperture and increasing magnification, one may glimpse some darker areas within the object’s envelope. The ansae themselves can be elusive and subtle in appearance. This is one of the brightest planetary nebulae in the sky and is a popular object for both visual observers and imagers as well. Being one of the few such objects in which observers are very likely to visually see color also makes it an attractive target in the night sky.


NGC 7507 (Sculptor, elliptical galaxy, mag=10.4, size=2.8’x2.7’, SBr=12.3):
NGC 7513 (Sculptor, barred spiral galaxy, mag=10.6, size=3.2’x2.1’, SBr=12.4):
These two galaxies in eastern Sculptor make a fine duo in the same field of view at only about 18’ apart. NGC 7507 lies southwest of NGC 7513, and is located not quite 3.5° northeast of mag 1.2 Fomalhaut (Alpha Piscis Austrini).

NGC 7507 will present a small round diffuse glow, as is typical for elliptical galaxies. Look for a small brighter core within the galactic disk. About 18’ to the northeast and within the same field of view you should pick up NGC 7513. Contrasting with the other galaxy in the view, this one presents a more elongated oval in the WSW orientation. It too is moderately bright for a galaxy and could likely reveal a small brighter core region within its disk. You should notice a wide pair of stars (mag 7.9 and 10.4) just south of the galaxy which adds to the curiousness of the view.

Interestingly both galaxies were not discovered by the same observer at the same time. Despite being relatively close together in the sky and of similar brightness, William Herschel discovered NGC 7507 in 1783 and Albert Marth discovered NGC 7513 in 1864. I find that a very curious little fact indeed.


IC 5148 (Grus, planetary nebula, mag=11.0, size=2.2’, SBr=12.4):
This is indeed a curious object, with its thicker annulus and smaller dark central “hole.” A mag 10.3 star (PPM 302060) sits just under 2’ SSW of the nebula’s center and helps identify the field. Using an O-III line or narrow-band nebula filter will improve the view of this object, and large apertures may reveal its dim mag 16.5 central star. It is fairly large for a planetary nebula and can have a ghostly appearance in the eyepiece with smaller apertures and without a filter. Larger apertures begin to reveal its true beauty. Just over 1° WNW of mag 4.5 Lambda Gruis, this dimmer planetary is sometimes referred to as the “Spare Tire Nebula” due to its thick annulus and dark center.

Discovered in 1894 by noted Australian amateur astronomer Walter Gale, it was assigned the identifier of IC 5150 by Dreyer. Then in 1897 it was independently discovered by Lewis Swift and given the secondary identifier of IC 5148 by Dreyer. Though normal protocol would dictate it be known by the identity assigned the original discovery (IC 5150), almost all sources utilize the secondary identifier of IC 5148. One has to wonder if this is because Swift was a professional astronomer, while Gale was a “mere” amateur. Both gave positions that were more or less equally inaccurate, but Gale’s description was spot on and thus he should be given credit and the assigned IC identity used as the primary. But unfortunately history is not always fair.


That is all for this time around. I hope you enjoy adding the above objects to your observing/imaging plans for September and October. Getting a little off the beaten path is a good way to challenge your observing skills and add some spice to your nightly sky searches. Good luck and let us know how it goes!

[messier 111]

even if I don't do photography, I love reading the content, always so instructive, thx.

[kt4hx]

even if I don't do photography, I love reading the content, always so instructive, thx.

Thank you Jean-Yves, and glad that you find this informative. However, you certainly do not need to do astro-photography to participate. I do not do AP either, and have always been a visual observer. This is for everyone, whether they do purely visual, sketching and/or AP. This is for everyone no matter their primary interest. The goal here is to get people thinking about objects that they may not know about or consider, and add them to their regular nightly pursuits. Take care and I hope you will give them a try. Good luck!

[Graeme1858]

Even though it's not yet September, I'm out trying to capture Saturn at opposition and the neighbour's bush is in the way. Saturn is quite low. So I thought I would have a quick grab at IC1590!

Here's a preliminary NINA stretch screen grab of a red filter capture:

Clouds are drifting over and I keep loosing my guide star but I should get enough data to give an appreciation of this lovely target.

Graeme

[kt4hx]

There you go Graeme! Most definitely that is IC 1590 in the center of NGC 281 (Pac Man Nebula). Look forward to your refinement of the data. Well done!

[kt4hx]

Since Graeme got the ball rolling with IC 1590 and NGC 281, I thought I'd post my own observing notes for this pair from back in Oct of 2016, using my 12 inch dob at the dark site area. Since its been almost seven years now since I last looked at them, perhaps it is about time I revisited when I can get back over there this autumn. Anyway, here are the first two objects for the northern section of the challenge according to my then seven year younger observing eye!


IC 1590 (Cassiopeia, open cluster, mag=7.4, size=4.0), type=III1m: Swinging to mag 2.2 Alpha Cassiopeiae (Shedir), I swept a little over 1.5° east to this bright curve of four stars, the open cluster IC 1590. While the cluster was dominated by the bright curve of stars, there were numerous other dimmer suns tossed about the field. The cluster was bright and detached from the field. This cluster energizes the emission nebula NGC 281 (Pac Man Nebula), and at 84x with the O-III filter, I could easily see the cluster was swaddled in a patch of nebulosity.

NGC 281 (Cassiopeia, bright nebula, mag~??, size=35.0’ x 30.0’): The famous Pac Man Nebula surrounds the open cluster IC 1590. When viewed at 84x with an O-III filter, it appeared mostly rounded in shape, though its southwestern side appeared to have a bite out of it – reminiscent of its nickname. Overall it was easy to see, despite the moon’s presence. Dropping in my new DGM NPB, the view was quite similar to that using the O-III, with neither seeming to give a noticeable advantage over the other. After my eye had acclimated to the view, the nebula was not too difficult to see after removing the filter, though of course the filter certainly made the task much easier.

[Graeme1858]

That's a good read Alan. Must be fun to see the Pacman appear through the OIII filter!

Here's my limited time, (45 minutes integration (6x3minL, 3X3minR, 3X3minG, 3X3minB)) LRGB version.

Looking forward to having a go at the Blinking Planetary Nebula.

Graeme

[kt4hx]

Now that is nicely done Graeme. Beautiful detail and depth of field and I really like it!

While the level of detail I can get visually is limited as compared to a well tuned image, there is still something very special for me about seeing it directly with the eye. I think that is why I've remained a visual observer, even in this day and age. I guess I am simplistic that way.

[Graeme1858]

There is something special about allowing photons into your eye that have travelled across the universe for millions of years!

Graeme

[Graeme1858]

Here's my first capture of the evening:

Yeah, thanks Musky!

Other than that, it's said we're about to enjoy an "Indian summer", so I have a week of clear sky imaging opportunity to go after this target!

Graeme

[kt4hx]

Since I already posted an observation of NGC 281 and IC 1509, I will now post some of my experience with the remaining northern objects for this DSO Challenge.

For NGC 7209, I was observing in October of 2016 from our then Bortle 5 quality backyard with the AD12 dob:

NGC 7209 (Lacerta, open cluster, mag=7.7, size=25.0’, class=III1p): Sweeping about 4.5° southwest from 4 Lacertae and almost 3° west of 2 Lacertae (mag 4.6), this large and bright cluster was another easy find. Well detached, viewed at 84x it presented a very rich assembly of about 40 to 50 stars with many nice pairs and triples tossed to and fro in the field. There was a dominant curvy line of about 15 to 20 stars ranging from 9th to 11th magnitude that snaked its way through the center. I found it quite an interesting and pretty cluster.


For NGC 6826 I was observing at our dark site house in late May of 2019 using my 17.5 inch dob:

NGC 6826 (Cygnus, planetary nebula, mag=8.9, size=0.5’, SBr=7.1):
Since I was near the so-called “Blinking Planetary” I decided to stop a moment to take a gander. At 110x it was bright and large in the field of view as a pale blue orb, with its mag 10.4 central star very obvious. With this aperture the blinking effect is not as noticeable as with smaller apertures. Using direct vision there is some shrinkage of the planetary envelope and increase of central star visibility, but it’s not as prominent. When viewed with averted vision the envelope did increase in size and the presence of the central star decrease, but again, the differences were not as noticeable as with less aperture. Nonetheless, it was still a pretty object worthy of a short detour.


For NGC 6946, I have two observations. The first is from late September of 2013 in our then Bortle 5 skies at home using the Z10 dobsonian. The second is from late May of 2019, using the 17.5 inch at our dark site house. I used both of these to show the contrast in terms of both aperture and dark skies, with the latter being the more important:

NGC 6946 (Cygnus, spiral galaxy, mag=8.8, size=11.5’x9.8’, SBr=13.8):
Sweeping southeasterly through mag 7.2 HD 196085, I found the face-on spiral galaxy NGC 6946. Though it straddles the Cepheus-Cygnus border, it is officially assigned to Cygnus. Glowing at apparent magnitude 9.1 with a dim surface brightness of 14.1, it was found at 69x as a dim, but noticeable roundish glow. It responded well to averted vision, with the core area brightening noticeably. Using 89x, the core appeared brighter without using averted vision, and it grew in size. At 114x to 142x, it became brighter and larger yet, but still remained somewhat dim, and diaphanous in appearance.

NGC 6946 (Cygnus, spiral galaxy, mag=8.8, size=11.5’x9.8’, SBr=13.8):
I now turned to the IDSA chart 9-left to continue on with my journey. In locating the field for this galaxy, which was easy enough, I immediately noticed that the view in this direction and elevation was much cleaner, which bode well for the last part of my journey. Aiming the scope at mag 4.3 Eta Cephei, I slipped SSW 2° and the galaxy slid into view. It was large and diaphanous in appearance. I settled in with 110x to study it a few moments.
I have only observed this one from our moderately light polluted back yard with the 10 and 12 inch, where it was challenging as a very dim round patch of haze. In this case, with more aperture and significantly darker skies, it was wonderful. It presented as a large and bright oval that had a diffuse appearance. As I continued to observe its spiral structure began to take form to my eye. Not in a bold manner, but rather in a subtle sense. I could detect the delicate swirl of its arms arcing outward from a core that exhibited a very slight increase in brightness. Beautiful and subtle it was such a graceful object, like fine grain sugar spun into cotton candy.


That completes my observations of the northern objects for this edition. I will report on the southern objects I've observed at another time. I hope you will add these objects to your "to-do" list and give them a look when you can. Good luck!

[Graeme1858]

Nice one Alan.

Your Fireworks Galaxy visual descriptions also describe the single subframe images I was getting last night. I don't remember seeing NGC6946 visually, although I might have in my 10" dob, non notetaking days! But I have captured it before, a couple of years ago, it wasn't a good night for astrophography, it was too windy, but it was November 5th, fireworks night here in the UK, so I had to go for it! I'm looking forward to a week of good weather here so I'm hoping I can capture a quality image of this subtle but beautiful galaxy with my new camera!

Here's a stretched and curves contrast adjusted version of the above showing the shape of the galaxy:

Great targets this month Alan.

Graeme

[kt4hx]

Thank you Graeme. Your image does indeed highlight the subtlety of NGC 6946. Visually its delicate structure will never match the more in your face presentation of something like M51. Then again, there is something intriguing and special about the more diaphanous structural details present in the delicate lower surface brightness galaxies such as NGC 6946, M101, NGC 2403 and IC 342. In your image is that streak a meteor or satellite?

[Graeme1858]

In your image is that streak a meteor or satellite?

I'm pretty sure it's a satellite but there's one in another frame that narrows at both ends, so that's either a meteor or a rotating piece of space hardware.

Graeme

[Graeme1858]

Here's Caldwell 12, NGC6946, the Fireworks galaxy. Captured over three nights this week and last week, each time packing up before the night was over, due to the high humidity causing USB connections failures!

Graeme

[kt4hx]

Here's Caldwell 12, NGC6946, the Fireworks galaxy. Captured over three nights this week and last week, each time packing up before the night was over, due to the high humidity causing USB connections failures!


NGC 6946 Fireworks Galaxy_01_03_TSS.jpg



Graeme

That is a fine image of NGC 6946 Graeme, very well done my friend. It does highlight the ethereal beauty of this particular galaxy. I like that you captured many of its HII star birthing regions in the arms. It is a shame that I could never see it quite to that level of detail visually. But between what I have seen coupled with your image, it solidifies its position as one of my favorite galaxies.

[Mirrorgirl]

Hi there

Here's a image of the Pacman nebula, i gathered 120x60 seconds and 22x120 seconds, i used Bills sho and processed it in pixinsight and photoshop, i also had to do some star hopping as i am having trouble with alignment, here it is




Thanks

Rhoda

[kt4hx]

Hi there

Here's a image of the Pacman nebula, i gathered 120x60 seconds and 22x120 seconds, i used Bills sho and processed it in pixinsight and photoshop, i also had to do some star hopping as i am having trouble with alignment, here it is

Thanks

Rhoda

Thank you for the very nice image Rhoda. You captured a lot of detailed structure within the complex. Plus you also showed your skills at star hopping to find the field - well done!

[Juno16]

Hi Alan,

I can’t see NGC 281 in the eyepiece, but I can photograph it.
I imaged this last week and it even has IC 1590 included (see https://theskysearchers.com/viewtopic.p ... 71#p254171).

Greame pointed me here and thanks for posting this thread.

[kt4hx]

Hi Alan,

I can’t see NGC 281 in the eyepiece, but I can photograph it.
I imaged this last week and it even has IC 1590 included (see https://theskysearchers.com/viewtopic.p ... 71#p254171).

Greame pointed me here and thanks for posting this thread.

Excellent image Jim, and I fully get about not being able to visually see certain objects. I cannot see it from home any longer either. But your image is certainly well processed and captures nicely the beauty of this object. Well done and I hope you will keep contributing to our little challenge threads. Thank you my friend.