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In Search of Spiral Arms in the Brightest Galaxies, the story so far... (Night Vision)

NV observing report
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#1 alanjgreen

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Posted 11 April 2019 - 05:53 AM

Dates: January to April 2019
Scope: 20” f3.6 Lukehurst Dob with Paracorr (fl = 2089mm & f4.1).
Night Vision: PVS-14 with Photonis 4g INTENS.
Eyepieces: Plossl 55mm (f2 x38)
Filters: None

 

 

“Ain’t No Mountain High Enough”

Galaxies are my main interest in the night sky. I have changed my equipment several times over the years and each change is always driven by a desire to see spiral arms in galaxies.

 

The equipment being used to fulfil my desire currently is a 20” f3.6 dobsonian with PVS-14 Night Vision Device attached to a 55mm TeleVue Plossl giving me x38 magnification and an “effective” focal ratio of around f2.

 

In early January, I picked up a list of the 200+ brightest galaxies from cloudynights and began working my way through them. The clouds and the moon have impacted my progress but I am now passed the 100 mark so I thought it was worth making an interim posting while galaxy season is still above us, just in case anyone wants some inspiration for their target choices?

 

As an aside, I have also been observing “other neighbouring” galaxies recently which has resulted in some nice finds, so I am now also “adding” to the initial list as I go.

 

 

It is also worth noting that my skies are SQM 21.6 for comparison purposes.

 

 

Interim findings.

I have graded all galaxies observed from 0 – 3 where 0 means “nothing to see here” and 3 means “spiral arms directly observed”.

 

 

Grade 3 galaxies (“Can’t Take My Eyes Off Of You”).
[spiral arms directly observed]

 

M51
M65
M66
M81
M90
M94
M95
M96
M99
M100
M101
M106
M109
NGC2403
NGC2903
NGC3184
NGC3628
NGC3631
NGC3726
NGC3728 - given as Mag 14+ in sky safari, but it turns out that its Mag 10+ in Ha smile.gif
NGC3893
NGC3896
NGC3953
NGC4278
NGC4449
NGC4559
NGC4565
NGC5248
NGC5371

 

 

Grade 2 galaxies (“Something In The Air”)
[Arm detail hinted in direct or with averted vision. These galaxies may be a grade 3 on the right night with the best conditions]

 

M61
M64
M82
M88
M91
M98
M104
NGC2537
NGC2681
NGC2768
NGC3294
NGC3344
NGC3373
NGC3596
NGC3646
NGC3675
NGC3686
NGC3718
NGC3729
NGC3813
NGC3938
NGC3945
NGC4013
NGC4051
NGC4214
NGC4216
NGC4293
NGC4389
NGC4490
NGC4517
NGC4535
NGC4536
NGC4618
NGC4625
NGC4725
NGC4762
NGC5005
NGC5364
NGC5383
NGC5746
NGC5907

 

 

"He Ain't Heavy, He's My Brother"

Here are some Sky Safari Observing Lists!

Attached File  Grade 3 Galaxies - Copy.skylist.txt   7.76KB   24 downloads

Attached File  Grade 2 Galaxies - Copy.skylist.txt   10.42KB   8 downloads

 

You need to remove the ".txt" from the end of the filename then email them to your device (that has Sky Safari installed), when you open the .skylist in the email app on your device it should ask you if you want to send it to Sky Safari. HTH!

 

 

"I'm A Believer"

I know that not all observers are happy about the use of Night Vision technology and do not see it as "visual" observing but the fact that I have stood at my telescope and seen spiral arms/dust lanes (or decent hints of them) in all those galaxies listed above speaks for itself.

 

As a galaxy man, I can smile as I say that I have "uttered expletives" and "broken out some cheeky grins" over the last 3 months (of galaxy observing ) as the once hidden spiral arms have come into my view!

 

The only real downside of the NV approach is the lack of magnification meaning that all galaxies are pretty small in the eyepiece but its amazing when you seen the curves of the tiny spiral arms that even these small targets can reveal.

 

I will publish another (longer) version in the next twelve months as my exploration of the remaining 100+ bright galaxies plus nearby neighbours continues...

 

Hopefully someone willl find this useful!

 

Clear Skies,

Alan


Edited by alanjgreen, 11 April 2019 - 12:02 PM.

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#2 Migwan

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Posted 11 April 2019 - 07:35 AM

I have a case of analysis paralysis between NV or a  BIG DOB.  Luckily, neither is happening for awhile, so diazepam not yet required. 

 

On a very rare night at a dark site, I clearly saw the spiral arms of M31 using an ST80 with a 24ES68.  That only managed to rile my disorder a bit.

 

So self pity aside, I really feel for anyone trying to decide between NV, BIG DOB or AP.  That must be pure hell.  jd


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#3 spencerj

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Posted 11 April 2019 - 08:09 AM

Or . . . you just get the big dob and then add night vision later lol.gif



#4 alanjgreen

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Posted 11 April 2019 - 09:09 AM

I have a case of analysis paralysis between NV or a  BIG DOB.  Luckily, neither is happening for awhile, so diazepam not yet required. 

 

On a very rare night at a dark site, I clearly saw the spiral arms of M31 using an ST80 with a 24ES68.  That only managed to rile my disorder a bit.

 

So self pity aside, I really feel for anyone trying to decide between NV, BIG DOB or AP.  That must be pure hell.  jd

You may find that NV will work well with the CPC1100 (giving decent image scale). I know that @Gavster is having fun with his C11 + reducer + 55mm Plossl + NV from London. If you search around cloudynights there are some posts of his where he has included phone images of galaxies (using the C11). Worth a look...

 

I would get the NV first, use it will all existing scopes as it will "improve" things. Then add faster focal ratio scopes if you need to with a specific purpose/target in mind...

 

I used to own a CPC1100 and maybe looking back, if I had had the NV first, I may not have got the 20" dob at all. It just shows that we never know what is around the corner?

 

Alan



#5 Jeff Morgan

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Posted 11 April 2019 - 02:45 PM

"I'm A Believer"

I know that not all observers are happy about the use of Night Vision technology and do not see it as "visual" observing but the fact that I have stood at my telescope and seen spiral arms/dust lanes (or decent hints of them) in all those galaxies listed above speaks for itself.

 

As a galaxy man, I can smile as I say that I have "uttered expletives" and "broken out some cheeky grins" over the last 3 months (of galaxy observing ) as the once hidden spiral arms have come into my view!

 

The only real downside of the NV approach is the lack of magnification meaning that all galaxies are pretty small in the eyepiece but its amazing when you seen the curves of the tiny spiral arms that even these small targets can reveal.

 

Excellent post, and thank you for the updates! A welcome dose of real observational data to dismiss the mis-information from people who have little (or no!) hands-on experience technology. But let's not dwell on that. Suffice it to say that as more observers acquire the technology the Old Wives Tales are being put to rest.

 

Not to say there are not nuances. And in my case, expectations have been my own worst enemy (hardly different than when I upgraded from 12.5" to 16"). Once one sees what a NV eyepiece does for nebula and star clusters, it sets an enormously high bar. Galaxies are a somewhat different animal.

 

On the surface, one would expect strong success based on the spectrum of galaxies and the response curve of the technology:

 

http://www.ceoptics....ech_report.html

 

Indeed, I do see results similar to what this report states with each morphology.

 

But there are some key differences vs. intra-galactic targets. While galaxies and nebula are both (observationally) extended objects, galaxies emit across the spectrum.

 

Unfortunately, light pollution also emits across the spectrum. From my Bortle 5 (rapidly becoming 6) skies, dropping in a h-alpha filter offers phenomenal results on nebula. No filtration Silver Bullet for galaxies (yet). Improvement is definite, but less dramatic vs nebula. Long Pass helps. Dark skies helps more.

 

For star clusters, I can boost the magnification significantly with small penalty. Not so with spiral arms. I suppose the good news is that when you can avoid averted vision (whether through aperture or NV), direct vision offers 3x the resolution, so the magnification issue doesn't bit quite as hard.

 

As you say, magnification will be limiting on seeing arms in small galaxies (with the definition of "small" probably being aperture-dependent). But from my backyard, switching out to my Leica Zoom is not going to make the difference either. Dark skies again become a key success predictor.


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#6 Jeff Morgan

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Posted 11 April 2019 - 02:54 PM

I have a case of analysis paralysis between NV or a  BIG DOB.  Luckily, neither is happening for awhile, so diazepam not yet required. 

 

On a very rare night at a dark site, I clearly saw the spiral arms of M31 using an ST80 with a 24ES68.  That only managed to rile my disorder a bit.

 

So self pity aside, I really feel for anyone trying to decide between NV, BIG DOB or AP.  That must be pure hell.  jd

 

There is a good case for either as a first step. Money and Logisitcs being the largest players. Beyond that, knowing what I know now ...

 

  • If galaxies were my forté I would say big scope first. NV second. There is a certain minimum aperture threshold to play the Galaxy Game effectively. For me, 16" doesn't cut it.
  • For more balanced observing programs, I would say NV first, big scope second. I would also go this direction if you found that the burden of getting to dark skies was cutting into your astronomy opportunities.

 

But seeing what the AP guys are doing these days - that is going to net you more arm detail than any other approach. Lots of work and Delayed Gratification though.


Edited by Jeff Morgan, 11 April 2019 - 02:56 PM.


#7 slavicek

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Posted 11 April 2019 - 10:53 PM

Alan, thanks for the report and list of targets. I am adding them to my observing lists. I have yet to try NV on galaxies, so I lack the experience but why don't you try higher magnification - that 55mm plossl is only like 40x? To get different magnifications I plan to use barlows with mine NV (MOD3).


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#8 alanjgreen

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Posted 12 April 2019 - 03:28 AM

Alan, thanks for the report and list of targets. I am adding them to my observing lists. I have yet to try NV on galaxies, so I lack the experience but why don't you try higher magnification - that 55mm plossl is only like 40x? To get different magnifications I plan to use barlows with mine NV (MOD3).

Slavicek,

The key to seeing spiral arms with NV is focal ratio. You need to go fast as you can go to see the arms.

 

The 55mm plossl acts as a 0.5x reducer and gets me to the fastest speed possible in all my scopes.

 

There are a few bright edge-on galaxies that can be almost as good with my Panoptic 35mm (acts as x0.7 reducer) but the side-on are never as good as with the 55mm due to the slower effective focal ratio. M51 is bright enough to take the 35mm but still the 55mm plossl beats it for details visible.

 

I am afraid that the Barlow approach will have the effect of reducing the effective focal speed and you will see diminishing returns as you reduce the focal speed.

 

With NV you just have to accept smaller scale because the faster focal ratios mean greater detail can be seen in spiral arms  (seems illogical but that’s the way it is).

 

Alan


Edited by alanjgreen, 12 April 2019 - 03:30 AM.


#9 Jeff Morgan

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Posted 12 April 2019 - 09:49 AM

To get different magnifications I plan to use barlows with mine NV (MOD3).

 

I got to thinking that galaxies consist primarily of stars, and as point-source objects they could take some magnification and be less sensitive to effective focal ratio (like clusters do.)

 

By chance the first galaxy I tried that approach with was M82. Already bright, large, good surface brightness. And it does benefit from a barlow with lots of detail offered.

 

Unfortunately, that is about the only galaxy I have tried that benefits from more magnification. Perhaps there other high surface brightness or dust lane objects where that may benefit and I have not run across them yet.

 

But largely the object class does not behave as a large collection of point-sources. Rather, it behaves like an extended object.

 

I would not discourage you from trying ... you might find cases were it is beneficial (and hopefully tell all of us about it!) But temper your expectations.


Edited by Jeff Morgan, 12 April 2019 - 09:51 AM.


#10 slavicek

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Posted 14 April 2019 - 10:24 PM

I am afraid that the Barlow approach will have the effect of reducing the effective focal speed and you will see diminishing returns as you reduce the focal speed.

 

With NV you just have to accept smaller scale because the faster focal ratios mean greater detail can be seen in spiral arms  (seems illogical but that’s the way it is).

Yes, it seems to me illogical, so, even thou I do believe you I will have to try it and see for myself  smile.gif



#11 Gavster

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Posted 15 April 2019 - 08:11 AM

You may find that NV will work well with the CPC1100 (giving decent image scale). I know that @Gavster is having fun with his C11 + reducer + 55mm Plossl + NV from London. If you search around cloudynights there are some posts of his where he has included phone images of galaxies (using the C11). Worth a look...

 

I would get the NV first, use it will all existing scopes as it will "improve" things. Then add faster focal ratio scopes if you need to with a specific purpose/target in mind...

 

I used to own a CPC1100 and maybe looking back, if I had had the NV first, I may not have got the 20" dob at all. It just shows that we never know what is around the corner?

 

Alan

Yes I do really enjoy my C11 with reducer and 55mm plossl which gets me around 40x mag (f3.3) and shows quite a few galaxies at decent scale. In fact in many ways I prefer my c11 nv setup to me 16inch dob nv setup, SCTs are very good for compact easy to use aperture which I think is a major benefit for these type of objects using NV.

Here's the link with some of my observations/phone images.

https://www.cloudyni...n-and-galaxies/



#12 alanjgreen

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Posted 26 April 2019 - 03:41 AM

I managed a couple of hours under decent skies last night and ran through the "grade 3" list, there are some errors that I need to correct:

 

NGC3896 is not a "3" (more of a "1")

NGC4724 is a "3"

NGC4728 is a "0" but is next to NGC4724 and I had them mixed up!

 

Therefore, my current grade 3 list is:

M51
M65
M66
M81
M90
M94
M95
M96
M99
M100
M101
M106
M109
NGC2403
NGC2903
NGC3184
NGC3628
NGC3631
NGC3726
NGC3728
NGC3893
NGC3953

NGC4274 *NEW*
NGC4449
NGC4559
NGC4565
NGC5248
NGC5371

NGC5746 *NEW added 12Apr *

NGC5907 *NEW added 12Apr *

 

Updated Sky Safari observing list here: Attached File  Grade 3 GalaxiesApr26.skylist.txt   8.06KB   6 downloads

 

Clear skies,

Alan


Edited by alanjgreen, 26 April 2019 - 03:46 AM.



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