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Hydrogen clouds, 6" Wide-field Refractor and NV (Report)

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#1 blackhaz

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Posted 16 July 2021 - 04:08 PM

I've been an amateur astronomer for fifteen years, but I think only the last few nights I was priviledged to observe Milky Way's hydrogen regions in all their glory - thanks to NV. The setup was:

  • 6" TS f/5.9 Achromat on TS alt-azimuth mount 
  • PVS-14 with Harder 2100 FOM tube
  • 67 mm TeleVue Plossl, giving 13X magnification and 3-degree field of view
  • H-alpha filters: Baader 7 nm and Antlia 3 nm
  • APM Amici prism for right angle correct orientation view
  • Interstellarum Deep Sky Atlas
  • Bortle class 4 site at Wembury Point, England (SQM showed 20.60). Transparency 6/7. 

 

214771063-10159551110556636-122900573118

 

Initially started with the summer classics - M57, M13, etc, but once I tried the 3 nm filter on the Gamma Cygni region, I literally couldn't pull myself from roaming around this region surrounding Sadr all the three nights. It was mind-blowing. IC1318 and Crescent both photographic in appearance. Glowing, cury, textured emission in high contrast to dark patches and filaments. The dark triangle near LDN889 not only apparent in form, but exhibiting detailed structure. The eyepiece view was quite similar to this picture, if you squint your eye a little: https://bit.ly/3hJ4Ws4

 

The Crescent showed doubling front in the north and Y-shape in the center, mottled body, almost "electric," I guess, due to the scintillation. Visually was very similar to this picture:
https://www.astrobac...-6888-Large.jpg

 

Numerous DWB emission clouds and the Sh2-101 Tulip in Cygnus were bright - the whole region all appeared as pierced and surrounded by faint hydrogen emission, which was also easily apparent in the eyepiece. The extent of the nebula seen far exceeded what was shown in the Interstellarum atlas.

 

NGC 7000 North America's Gulf was very detailed and at high contrast, with bright knots in Mexico and in the north. The IC5067 Pelican was bright, showing three protruding "fingers" and irregular shape. IC 5068, the Cygnus Arc, was bright and apparent, split into multiple irregular regions. IC5146 Cocoon was pretty bright, without much fine detail inside, and apparent central star. Looking at the Interstellarum Deep Sky Guide, I now see that on those emission nebulae I saw about similar level of detail to what Uwe Glahn saw in his 27" reflector. 

 

The wide field of the 6" showed the whole western portion of the Veil in its field, with irregular bright "claw" of IC1340. NGC 6974/9 with Pickering's Triangle, shown as visible from 12" aperture in the atlas, was pretty bright in the eyepiece. The eastern part had less detail, but its overall irregular shape easily seen. 

 

Ventured to IC1396 in Cepheus, it appeared very extended and pretty faint, I couldn't see much dark detail, although central round dark region was apparent. Sh2-132, Sh2-157 (bright), NGC7635 and NGC7538 all exhibited some degree of detail, but I am not too familiar with these objects, and left them for another occasion. I don't think I could see the bubble itself with certainty, but it's on a to-do list now.

 

Going south, M27 was bright and pretty compact, compared to vast hydrogen clouds of Cygnus. I won't mention myriads of well-known and obscure star clusters along the way. I think I could see into great "depth" and could observe less well-known NGC clusters well. (Dolidze-Dzimselejsvili 11 is a really peculiar alignment of stars!) Roaming along the Galactic equator, I have never seen so many stars in the eyepeice in my life. I own mostly Cassegrain designs, but f/5.6 reduced to f/2.3 is something else. Carpets, laces of stars!

I tried switching to "normal eyepiece", but literally couldn't see much, compared to the NV mode. The eye wasn't properly dark-adapted, and, to be honest, after the level of detail seen in NV it felt a little futile. I tried 7 nm H-alpha filter, but it showed significantly less detail than the 3 nm Antlia. From dark nebulae, Barnard's E (B142) in Aquila was apparent without filtering. Some dark nebulae, if overlaid on HII emission, were better seen with the hydrogen filter on.

 

The last night before returning home I explored Sagittarius, literally bumping into M22 very low on the horizon while scanning manually, and it was a sight to behold! Definitely a top globular in my book now, replacing M13, along with Sadr surroundings being visually more engaging and richer than even the great Orion Nebula! And then... M8 Lagoon was almost a live photograph - silky-smooth whirlpool, bright and detailed flower-like center with stars, dark patches - it's difficult to describe! Looking at monochrome photographs of the Lagoon, I think visually what 6" showed that night comes quite close. I could spend the whole night on that object alone (or the Sadr!) but that was my first overview "mission" so I had to move on. The M20 Trifid was very bright, almost laser-etched on the sky background with irregular patches dividing it easily seen as pitch-black filaments. This photograph is similar to what was seen in the eyepiece (although yes, there was noise in the tube, and it wasn't that deep, so squint to get an idea):
https://bit.ly/2TesrQo

 

In that area further, M17, Omega, was very bright and high-contrast as well - I could see the Omega shape in it, so now I finally get why it's called that, and the center emission region was extremely bright and knotty. M16 Eagle appeared as an eagle with wings open, and although there was lots of texture, I couldn't see Pillars of Creation that night, but definitely worth a try at a higher elevation and with a barlow.

 

Suddenly, my visual astronomy life is enriched with so many objects, exhibiting so many details. Comparing what I've seen with Uwe Glahn's and Ronald Stoyan's sketches in the Interstellarum Deep Sky Guide, on extended emission nebulae a 6" aperture with FOM 2100 NV under Bortle 4 sky shows more detail than unaided 27" reflector under very dark sky, and definitely exceeds 14". Could it get any better? On the way home, I had the opportunity to visit the Stonehenge!

 

Max

 

215956601-10159552864611636-454637502024


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#2 Eddgie

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Posted 16 July 2021 - 05:21 PM

I love a good observing report and this one was excellent! I know your excitement about seeing more stars than you ever thought possible.

 

Make sure you put some dark nebula on the list. My all time favorite is the Ink Spot and it is one of those places where you will get an enormous number of stars. This is a dark nebula so here you would want to run unfiltered or us a long pass.

 

Also, be sure to do some 1x!

 

Thank you for sharing this wonderful report with us!

 

Ed


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#3 blackhaz

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Posted 16 July 2021 - 05:54 PM

Ed, many thanks for mentioning the Ink Spot. Added to the list! I really wanted to do 1X but couldn't pull myself from the telescope. Will absolutely have to do this next time.

 

Max


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#4 a__l

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Posted 16 July 2021 - 06:22 PM

Eddgie, Good news for returning to this section after a long absence.


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#5 Trentend

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Posted 16 July 2021 - 06:25 PM

Great report. And here’s me thinking it’s not worth looking up this time of year with the bright skies! Finally sorted the C11 so looking forward to a darker site trip rather than the bortle 7/8 City centre viewing I normally have.


Edited by Trentend, 16 July 2021 - 06:25 PM.

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#6 slavicek

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Posted 16 July 2021 - 08:17 PM

Great report Max. Wait till you see Horse Head and Barnard loop around Orion. I'd suggest you go for 3x, 75mm lens instead of 1x, 25mm lens. My 2c.


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#7 blackhaz

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Posted 17 July 2021 - 02:03 AM

Trentend, having dark sky makes so much difference. Visual observing can be discouraging in city. C11 is awesome.

Slavicek, what lens do you use - any issues with backfocus? I have a 90 mm refractor which would give me 8X, but want something even shorter. 3X and 75 mm aperture sounds like fun.


Edited by blackhaz, 17 July 2021 - 02:04 AM.


#8 Joko

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Posted 17 July 2021 - 03:51 AM

Make sure you put some dark nebula on the list. My all time favorite is the Ink Spot and it is one of those places where you will get an enormous number of stars. This is a dark nebula so here you would want to run unfiltered or us a long pass.

Great review Max, very nice to read it.

As explained by Eddgie, you can add ink spot nebula (Barnard 86) to the next observing list. It's one of my favourite too, the field of view is full of stars and among them there is a dark cloud.

It's in Sagitarius, close to NGC6520.

More info here : http://www.deepskywa...ula-sketch.html


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#9 Jeff Morgan

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Posted 17 July 2021 - 01:08 PM

Great report!

 

Cygnus is an incredible NV playground.

 

Be sure to check out the Alpha-Gamma-Delta triangle, vast amounts of nebulosity there that resemble high cirrus Mares Tail clouds. Virtually unknown to the Conventional crowd.


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#10 slavicek

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Posted 17 July 2021 - 05:30 PM

Trentend, having dark sky makes so much difference. Visual observing can be discouraging in city. C11 is awesome.

Slavicek, what lens do you use - any issues with backfocus? I have a 90 mm refractor which would give me 8X, but want something even shorter. 3X and 75 mm aperture sounds like fun.

I use Kowa (Japan) 75mm f/1.8 lens.  13 deg FOV, perfect for Barnard loop.   3x is my handheld favorite. I epoxied Baader 48mm female adapter in front of the lens which allows me to place in 2" filters in front of the lens. Simply beautiful.

 

I use MOD 3 which has bit of an issue with back focus but so far I was able to solve all of these back focus related issues. I am not sure about PVS-14 back focus thou.

 

I also use NV with my refractors but NV really like FAST telescopes, so my f/3.3 Dob is my second favorite. Think Horse Head nebula...


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#11 AllStarez

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Posted 18 July 2021 - 10:58 AM

Max, thanks for writing your post, i loved it


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#12 PEterW

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Posted 18 July 2021 - 02:40 PM

1x and 3x will show different stuff and use a long pass 685nm to remove light pollution and show loads of stars even from “less than perfect” locations. Great report from another convert. Get a copy of Brackens Astrophotography Sky Atlas… it’s almost written for NV users in mind…. ;-)

Petwr
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#13 Jeff Morgan

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Posted 19 July 2021 - 03:07 AM

+ 1 on Bracken.



#14 Tyson M

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Posted 23 July 2021 - 11:34 AM

Very nice report!


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