TSS Bi-Monthly DSO Challenge for September/October 2022

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TSS Bi-Monthly DSO Challenge for September/October 2022

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Post by kt4hx »


Well folks it’s that time again, a new bi-monthly DSO Challenge is upon us. Over the next couple of months the northern folks are heading into autumn, with the promise of some reprieve from the heat and insects of summer. Nights will begin to get cooler and mosquitoes will abate, making for a more pleasant observing experience. Out southern friends will be heading into their spring season, which may involve increased cloudiness unfortunately.

For our northern targets we will visit the prominent constellation of Cygnus for a couple of very diverse objects, plus stop by the diminutive Delphinus for another. In the south we will visit Indus, Capricornus and Aquarius. I encourage everyone to make room in their observing, sketching and/or imaging plans to visit as many of these objects as you have access to from your specific location. Plus, I hope you will report back to this forum your results with these objects so everyone can share in your enjoyment and learn from your experiences.

So with that, let’s get going, and let me present the TSS DSO Bi-monthly Challenge for the months of September/October. I hope you enjoy pursuing these objects, no matter if you’ve never done so, or if they are old familiar friends from previous forays in the night sky. The key element here is the enjoyment of communing with the universe in a very personal way. So let’s get busy and have some fun out there. Good luck!


Northern Celestial Hemisphere

Messier 39 / NGC 7092 (Cygnus, open cluster, mag=4.6, size=31.0’, class=III2p):
This bright cluster is found in eastern Cygnus just over 9° ENE of Deneb. It was first recorded by Aristotle in 325 B.C., but Charles Messier is typically credited with its discovery in 1764. It also carries the designations of Collinder 438 and Melotte 236. Loosely structured, it is dominated by about 15 stars of 6th to 9th magnitude, with numerous dimmer stars scattered in the field. The overall appearance, particularly at lower magnification has a triangular shape. It can often be seen in small binoculars as a bright and loose collection of stars overlaying a distinct haziness of unresolved dimmer members. While not an impressive object overall, it is still certainly worth a look while one is foraging within the celestial swan’s waters. If you like sparkly stars (and who doesn’t!), then take a peek sometime.

NGC 6934 (Delphinus, globular cluster, mag=8.9, size=7.1, SBr=12.9, Class=8):
We now head into one of the smaller constellations (69th out of 88 in terms of area) in the sky, Delphinus the dolphin. Easily recognizable by its kite-like appearance it contains no Messier objects and is sometimes overlooked, particularly by beginners. What we will focus on here is the brightest of the globular clusters within the celestial dolphin. It can be located just shy of 4° south of mag 4.0 Epsilon Delphini (Aldufin). Visually this globular is fairly bright and moderately large in angular extent. As magnification and aperture is increased, one should start to see some appreciable resolution in its outer fringes, and across the orb’s face. The cluster’s core is small and moderately compressed. This object was discovered by William Herschel in 1785, describing it as a "beautiful object." His son John also observed it and described it as "a beautiful, very compressed, bright, round, globular cluster."

Veil nebula (Cygnus, supernova remnant, mag=7.0, size=3.0°, SBr=18.0):
The famous Veil Nebula is without a doubt one of the most intriguing and beautiful objects in the northern sky. It is the visible portion of the larger Cygnus Loop (catalogued as SNR G074.0-08.6 or Sharpless 103), which is the result of a supernova explosion over 10,000 years ago, the progenitor of which was over 20 times the mass of our own sun. It lay at a distance of approximately 2,400 light years. Its field is about 2.5° south of mag 2.5 Epsilon Cygni (Gienah). At about 3° in diameter its field is expansive.

In areas with significant light pollution it can be an extremely challenging object to detect visually, escaping detection. It is highly responsive to O-III line filters and to a slightly lesser degree with a narrow-band nebula filter. As light pollution becomes less an issue, it becomes more readily apparent. While it can be seen without a filter in darker skies, it truly comes into its own with the use of one. Because of its low surface brightness, the use of a filter boosts its contrast against the sky rendering a much larger portion of its intricate structure visible.

Typically this complex is viewed as having three main portions, the eastern, western, and central which consists of a triangular shaped section called Pickering’s Triangle or Wedge (Simeis 3-188). There are a total of six portions of the complex that appear in the NGC/IC catalogues, plus several other smaller knots and filaments. It is a visual treat beyond comparison if one is able to see it in its full glory. It contains very diaphanous and delicate filamentary structure unlike any other object readily visual to amateurs. I have added a link to an excellent Sky & Telescope article highlighting the structural details of the Veil complex to aid you in your own investigation of this amazing object. Good luck, it is time well spent.

https://skyandtelescope.org/astronomy-b ... il-nebula/


Southern Celestial Hemisphere

ESO 236-7 (Indus, open cluster, mag=7.0, size=30.0’, class=II3):
This open cluster is found in the European Southern Observatory Catalogue. The object is located just over 1.5° north of mag 4.4 Theta Indi. First plotted by Petrus Plancius the constellation Indus represents the “Indian”, though which indigenous group it supposedly represents is unknown. Visually the cluster is not particularly rich or overly detached from the stellar field. It is dominated by eight star ranging from 6th to 9th magnitude that straggle SSE to NNW, with several more of 10th and 11th magnitude dotting the field around the main grouping. Though not an outstanding visual treat, it still is a curious little grouping in a dimmer constellation known more for its galaxies. To aid you in locating this cluster, its J2000 position is: R.A. 21h21m28.0s, Dec. -51°48'42". Much like Messier 39 in the north, it is interesting to observe, but not especially memorable.

Messier 30 / NGC 7099 (Capricornus, globular cluster, mag=6.9, size=12.0, SBr=12.0, class=5):
We now travel to the celestial sea goat. Though the name Capricornus is Latin for "horned goat" or "goat horn" or "having horns like a goat's", it is typically referred to as a “sea goat” – half goat/half fish. Regardless, it is an obvious constellation in the southern sky, with its primary stars forming a very large triangular pattern to the east of Sagittarius. Though the constellation is home to many galaxies, it is best known in the DSO realm for this bright globular cluster.

It is easily observed from a goodly portion of the northern hemisphere as well, and presents a modestly large round glow with a tight core. It can often be picked up in a standard 8x50 RACI optical finder as a small non-stellar diffuse object. Upon inspection with the main scope, it should reveal some resolution in its outer halo, and one may notice a couple of streamers of stars emanating outward from the tightly packed core. While not the eye candy status of some larger, brighter globulars, it certainly is a beautiful little object to behold and is well worth the effort to locate. If you wish to add more of a challenge at this point, then try to find the globular Palomar 12, also in Capricornus. At mag 11.7 and only about 2.9’ in diameter, this wee little class 12 will test your mettle as a visual observer. Try for it 2° 25’ NNE of M30. This object is a true discovery of Charles Messier, with him first locating it in 1764.

NGC 7293 (Aquarius, planetary nebula, mag=7.6, size=16.2’x12.3 SBr=13.1):
Our final object for this edition of the challenge is a very popular and famous planetary nebula in the water bearer constellation. Though Aquarius is a large and relatively dim constellation, overall it does contain a few brighter stars, and certainly is home to a plethora of DSOs. Our interest here lies with the famous Helix Nebula. Very large for a planetary nebula, its listed visual magnitude can be a bit deceiving. Because of its large angular size, its reduced surface brightness limits its visibility when one is dealing with moderate to significant light pollution. As with most planetaries, use of an O-III line filter is extremely helpful. By design they boost contrast by passing the doubly ionized oxygen (O-III) lines prevalent within PNe, while severely restricting frequencies outside the designed pass band such as that of sky glow.

The nebula displays an annular structure, but unevenly so as some portions appear brighter than others. Particularly the western edge of the ring structure may seem dimmer as compared to the remainder. The magnitude 13.5 central star is fairly easily seen, and with larger aperture and increasing magnification it is possible to see upwards of a dozen foreground stars imposed upon the large nebulous disk.

This object has a bit of a checkered discovery history. The first “discovery” was by Karl Ludwig Harding in the 1823-24 time frame, ironically utilizing an 8.5 inch reflector built by William Herschel that was housed at the Gottingen University Observatory. He is given credit though no fewer than three other independent discoveries were reported because of the lack of knowledge of those previous discoveries. Though the object was included by John Herschel in his General Catalogue, it was never observed by him or his father William Herschel. This was quite likely because of its large size and resulting lower surface brightness.


With that, I will turn this little project over to you. Whether you are a visual observe like myself, someone who enjoys sketching at the eyepiece, or prefer the imaging side of our hobby, there should be something here for you. Be sure to let us know here how your endeavors turn out. Sharing our common experiences in the field is the most productive way for us to learn from one another. Keep looking up there friends cause that's where the good stuff is!
Alan

Astro Sky 17.5 f/4.5 Dob || Apertura AD12 f/5 Dob || Zhumell Z10 f/4.9 Dob
ES AR127 f/6.5 & ED80 f/6 on Twilight-II || Apertura 6" f/5 Newtonian on Twilight-I
TV Ethos 100° 21mm, 13mm || ES 82° 24mm, 18mm || Vixen LVW 65° 22mm
Pentax XW 70° 10mm, 7mm, 5mm || barlows
DGM NPB Filter || Orion Ultra Block, O-III and Sky Glow Filters || Baader HaB Filter
Primary Field Atlases: Interstellarum and Uranometria All-Sky Edition
---------------------------------------------------------------------------
"Astronomers, we look into the past to see our future." (me)
"Seeing is in some respect an art, which must be learnt." (William Herschel)
"What we know is a drop, what we don't know is an ocean." (Sir Isaac Newton)
"No good deed goes unpunished." (various)
"I have become comfortably numb." (Roger Waters)
Some people without brains do an awful lot of talking, don't you think?” (Scarecrow, The Wonderful Wizard of Oz)
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Re: TSS Bi-Monthly DSO Challenge for September/October 2022

#2

Post by John Baars »


On the twenty-ninth of August I was out again with my 120mm ED Skywatcher refractor. Amongst others I did NGC 6995 and 6992, with and without UHC filter. Under my local Bortle 8 skies without filter there was nothing to be seen. The UHC filter made a big difference. The Veil NGC 6992 and 6995 could be noticed.

When I was on holiday two weeks earlier in a darker part of the Netherlands a complete different view was presented to me. There, under Bortle 4 skies NGC 6992 and NGC6995 were visible with my 102mm Vixen refractor. Even without filter. With UHC filter installed in front of my diagonal it was more impressive.

I always use the trapezium of stars that lies on the border of NGC6992 to find it. Once I see them, I know 6992 is nearby. The sketch below is left/right inverted, like I see it in my refractor. I used a 30mm APM 80° eyepiece for 30X magnification in all cases for a 2,6 degree field of view. It generates an exitpupil of 3,33 mm and 4 mm in my 102mm and 120mm refractors respectively , enough for the UHC filter to function well.

There are three images:
1. The view in my 120 mm Evostar Skywatcher at home under Bortle 8/9 skies. Without filter. Nothing to be seen.

2. The view in my 102 mm Vixen on holidays under Bortle 4 skies without filter. Ex Aequo my 120mm under Bortle 8/9 with UHC filter.

3. The image in my 102mm Vixen on holidays under Bortle 4, with UHC filter.
NGC 6992 en 6995 final.jpg


Important lessons to be learned:
- An UHC filter is quite usefull under city circumstances. Beware: If you use ( not uncommonly) an exit pupil of 1 mm with your filter in the city, you'll still have trouble of observing faint emission nebula's. The exitpupil MUST be larger than your usually used one, for the filter eats light. So, the bigger exitpupil ensures that enough light is coming into your eye. 3 or 4 mm should do the trick. Sometimes even 5mm.
- A gasoline filter to a darker location is always preferable.

I hope you enjoyed it.
Telescopes in frequency of use : *SW Evostar 120ED F/7.5, * Vixen 102ED F/9, *grabngo: SW 102 Mak F/13, *OMC140 Mak F/14.3, on Vixen GPDX.
Most used Eyepieces: *Panoptic 24, *Morpheus 14, *Leica ASPH zoom, *Zeiss barlow, *Pentax XO5.
Commonly used bino's: *Jena 10X50 , * Canon 10X30 IS, *Swarovski Habicht 7X42, * Celestron 15X70, *Kasai 2.3X40
Rijswijk Public Observatory: * Astro-Physics Starfire 130 f/8, * 6 inch Newton, * C8, * Meade 14 inch SCT on EQ8, *Lunt.
Amateur astronomer since 1970.
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Re: TSS Bi-Monthly DSO Challenge for September/October 2022

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Post by kt4hx »


Thank you John and very nice comparison between locations and with/without the filter. I might ask, which specific UHC filter you are using? For the Veil, I've found an O-III line filter typically is a little better than a narrow-band UHC. However, I also have a DGM NPB filter (UHC-type) which has a decently narrow band width and passes the two main lines of O-III, so it does a very admirable job on this SNR complex. Agreed about the exit pupil recommendations, as these filters do restrict the passage of sky glow and starlight due to their narrow pass bands. I think that is something that really surprises a lot of beginners, the darkening of the field. Well done my friend and your contribution is very much appreciated.
Alan

Astro Sky 17.5 f/4.5 Dob || Apertura AD12 f/5 Dob || Zhumell Z10 f/4.9 Dob
ES AR127 f/6.5 & ED80 f/6 on Twilight-II || Apertura 6" f/5 Newtonian on Twilight-I
TV Ethos 100° 21mm, 13mm || ES 82° 24mm, 18mm || Vixen LVW 65° 22mm
Pentax XW 70° 10mm, 7mm, 5mm || barlows
DGM NPB Filter || Orion Ultra Block, O-III and Sky Glow Filters || Baader HaB Filter
Primary Field Atlases: Interstellarum and Uranometria All-Sky Edition
---------------------------------------------------------------------------
"Astronomers, we look into the past to see our future." (me)
"Seeing is in some respect an art, which must be learnt." (William Herschel)
"What we know is a drop, what we don't know is an ocean." (Sir Isaac Newton)
"No good deed goes unpunished." (various)
"I have become comfortably numb." (Roger Waters)
Some people without brains do an awful lot of talking, don't you think?” (Scarecrow, The Wonderful Wizard of Oz)
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Re: TSS Bi-Monthly DSO Challenge for September/October 2022

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Post by John Baars »


kt4hx wrote: Tue Aug 30, 2022 4:21 pm Thank you John and very nice comparison between locations and with/without the filter. I might ask, which specific UHC filter you are using?(...)
The brand is "Astronomik"
My OIII is a TS branded one, not the highest of quality. Maybe that is why I have a slight preference for my UHC Astronomik.
Telescopes in frequency of use : *SW Evostar 120ED F/7.5, * Vixen 102ED F/9, *grabngo: SW 102 Mak F/13, *OMC140 Mak F/14.3, on Vixen GPDX.
Most used Eyepieces: *Panoptic 24, *Morpheus 14, *Leica ASPH zoom, *Zeiss barlow, *Pentax XO5.
Commonly used bino's: *Jena 10X50 , * Canon 10X30 IS, *Swarovski Habicht 7X42, * Celestron 15X70, *Kasai 2.3X40
Rijswijk Public Observatory: * Astro-Physics Starfire 130 f/8, * 6 inch Newton, * C8, * Meade 14 inch SCT on EQ8, *Lunt.
Amateur astronomer since 1970.
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Re: TSS Bi-Monthly DSO Challenge for September/October 2022

#5

Post by kt4hx »


John Baars wrote: Tue Aug 30, 2022 4:57 pm
kt4hx wrote: Tue Aug 30, 2022 4:21 pm Thank you John and very nice comparison between locations and with/without the filter. I might ask, which specific UHC filter you are using?(...)
The brand is "Astronomik"
My OIII is a TS branded one, not the highest of quality. Maybe that is why I have a slight preference for my UHC Astronomik.

Could well be, as Astronomik is a known high quality product. The thing is with O-III filters, there is sound reasoning to have one of wider bandwidth and one of narrower bandwidth. They can be used under different circumstances to take advantage of their specific characteristics for circuit aperture/object combinations. While I am not a prolific filter user, since my main thing is galaxies, I do like to have some in my case for those times when I go after other types of objects.
Alan

Astro Sky 17.5 f/4.5 Dob || Apertura AD12 f/5 Dob || Zhumell Z10 f/4.9 Dob
ES AR127 f/6.5 & ED80 f/6 on Twilight-II || Apertura 6" f/5 Newtonian on Twilight-I
TV Ethos 100° 21mm, 13mm || ES 82° 24mm, 18mm || Vixen LVW 65° 22mm
Pentax XW 70° 10mm, 7mm, 5mm || barlows
DGM NPB Filter || Orion Ultra Block, O-III and Sky Glow Filters || Baader HaB Filter
Primary Field Atlases: Interstellarum and Uranometria All-Sky Edition
---------------------------------------------------------------------------
"Astronomers, we look into the past to see our future." (me)
"Seeing is in some respect an art, which must be learnt." (William Herschel)
"What we know is a drop, what we don't know is an ocean." (Sir Isaac Newton)
"No good deed goes unpunished." (various)
"I have become comfortably numb." (Roger Waters)
Some people without brains do an awful lot of talking, don't you think?” (Scarecrow, The Wonderful Wizard of Oz)
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John Baars
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Re: TSS Bi-Monthly DSO Challenge for September/October 2022

#6

Post by John Baars »


I did a small OIII and UHC shootout on The Veil NGC6992/6995 ,the Crescent NGC6888 and M27 the Owl nebula last evening.Transparency was not top, although the wind was NE, coming from the Atlantic Ocean. Instrument 120 mm ED Evostar, exitpupil 4 mm. And of course The OIII and UHC filter in front of the diagonal. ( as far away as possible from the eyepiece to prevent false reflections)

-On M27 the UHC won by far and very convincing. The contrast with the background was quite obvious. Slightly less in the OIII to my taste. Without filter M27 could be noticed.

-The Crescent area suddenly showed much more nebulous like structures in both filters. In the whole field, that is. These cloudy structures didn't look the same through the filters. With the UHC I could make out the Crescent as a vague drop of water, with the OIII this impression was less, but the visibility of the brighter Northern edge was slightly better though. Without filter no nebulosity was seen what so ever.

- On the Veil 6992 and 6995 ( the East Veil) there wasn't much of a difference. Without them nothing was seen, with them a very softly glowing beam of light was seen in both filters. Hardly visible because of the worse transparency in comparison with the first time. Too soft to make out any differences
Telescopes in frequency of use : *SW Evostar 120ED F/7.5, * Vixen 102ED F/9, *grabngo: SW 102 Mak F/13, *OMC140 Mak F/14.3, on Vixen GPDX.
Most used Eyepieces: *Panoptic 24, *Morpheus 14, *Leica ASPH zoom, *Zeiss barlow, *Pentax XO5.
Commonly used bino's: *Jena 10X50 , * Canon 10X30 IS, *Swarovski Habicht 7X42, * Celestron 15X70, *Kasai 2.3X40
Rijswijk Public Observatory: * Astro-Physics Starfire 130 f/8, * 6 inch Newton, * C8, * Meade 14 inch SCT on EQ8, *Lunt.
Amateur astronomer since 1970.
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Re: TSS Bi-Monthly DSO Challenge for September/October 2022

#7

Post by kt4hx »


Thank you John. A nice comparison on some challenging objects. Without a doubt filters do have an impact. How much of course has to do with the quality, design, proper application and experience of the observer. I have seen cases, as you mentioned, where the filter was the make or break factor. With you see something, without you do not. Well done.
Alan

Astro Sky 17.5 f/4.5 Dob || Apertura AD12 f/5 Dob || Zhumell Z10 f/4.9 Dob
ES AR127 f/6.5 & ED80 f/6 on Twilight-II || Apertura 6" f/5 Newtonian on Twilight-I
TV Ethos 100° 21mm, 13mm || ES 82° 24mm, 18mm || Vixen LVW 65° 22mm
Pentax XW 70° 10mm, 7mm, 5mm || barlows
DGM NPB Filter || Orion Ultra Block, O-III and Sky Glow Filters || Baader HaB Filter
Primary Field Atlases: Interstellarum and Uranometria All-Sky Edition
---------------------------------------------------------------------------
"Astronomers, we look into the past to see our future." (me)
"Seeing is in some respect an art, which must be learnt." (William Herschel)
"What we know is a drop, what we don't know is an ocean." (Sir Isaac Newton)
"No good deed goes unpunished." (various)
"I have become comfortably numb." (Roger Waters)
Some people without brains do an awful lot of talking, don't you think?” (Scarecrow, The Wonderful Wizard of Oz)
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