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Galaxy first light in NV

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#1 Tim M

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Posted 19 March 2018 - 11:38 PM

Well, I was already totally sold on NV for real-time H-a observing.  But what about Galaxies from my red zone 18.9 SQM-L backyard?  I’ve heard NV ‘somewhat helps” for galaxies, but how would that play out for me?   Sunday night was clear but still subfreezing, with less breeze than the prior two nights.

 

All observations, unless otherwise noted, with 12 inch f4.9 dob (tracking, but not go-to), TV 55mm Plossel, OMNI VII tube NV, unfiltered.  All magnitudes quoted from SkySafari (not known for magnitude accuracy but it is what I work from at the scope).

 

As usual, start off with bright targets – M82/M81.  M81 was bright nucleus with large extended haze.  Gain control really varies the visible extent of the galaxy’s size, up to about 75% max gain, above which only added more LP.  Inside the galaxy a few additional bright points were observed.  I assume these were dim foreground stars, but I need to consult some better charts.  M82 was the expected slender shape, with the central “gap” of active star formation bisecting the galaxy.  At only 27x, there wasn’t much additional detail to be seen in M82, but at almost 2 deg FoV, a third galaxy shared the view – NGC 3077, a mag 9.9 spiral galaxy the other side of M81 from M82.  While only the non-stellar bright core was visible, the “three-in-the-view” reminded me of the Leo Triplet.  Further away from these 3, I tried for the mag 10.4 IC 2574.  Supposedly larger then M81, but I couldn’t see it (some chance I star-hoped incorrectly).  But from M81, I was able to hop up to the smaller NGC 2976, mag 10.2, with the core clearly visible.

 

Down to M51/NGC5195.  Both easily visible, with M51 brighter on the side opposite its companion, including several brighter points noted along the outer edge – these I believe hold some promise of star forming regions, vs. mere foreground stars.  Very faint spiral structure was visible periodically with averted vision. Never saw that before!

 

What about M101?  I never was able to see this galaxy from my previous SQM-L 19.5 backyard.  With NV, it was clearly visible, but little more than the core, with some faint haze and scattered brighter points around a large diameter.  But the cores of two much smaller nearby galaxies were there for the taking – mag 11.5 NGC 5473, and mag 11.4 NGC 5485.

 

Over to CV and Cocoon, NGC 4490, and also mag 11.9 NGC 4485, together know as Arp 269.  I had just observed these 2 under darker (~ SQM 20.2) skies, and was eager to see how NGC 4490’s distorted shape would look like with NV.  The good news was that the fainter NGC4485 was visible.  The bad news was the I really couldn’t see as much detail on 4490.  At 27x, the image scale was rather small so in addition to the 55mm, I tried both a TV 35 Pan and a TV 17 Nagler, both of which provided less detail, not more.  The effective f ratios are about f/2.4, f/3.8, and f/6.  I’ve heard that NV likes best to run fast, so I determined to stick with the 55mm for the rest of the night.  I also observed the pair visually in each eyepiece, without NV.  As expected, the 17mm provided the best view, with NGC 4485 visible direct, but faint.  But the 55mm + NV was at least as good, if smaller.

 

Swinging down towards M94, and another large galaxy pops into the NV field – mag 10.8 NGC 4618, along with the close by core of the smaller NGC 4625, mag 12.4.  About this time I began to feel like NV was going to definitely allow me to observe a whole lot of galaxies in spite of my frustrating grey skies!

 

West to the Leo Triplet.  Three in the view, just as they should be, M65, M66, and the edge-on mag 9.5 NGC 3628.  I forgot at the time, but I must go back and see if the dust lane in 3628 is visible.  And about a field further west, mag 10.9 NGC 3593 (at least the core).

 

On the charts, I noticed a group of smaller galaxies further north in Leo.  NGC 3608 mag 10.8, NGC 3607 mag 9.9, and NGC 3632 mag 11.0, all visible as fuzzy cores and little else.  And tiny NGC 3605, mag 12.3, also checked in faintly, but non-stellar, just off of 3607, making it easy to find.

 

It was getting late on a work night, so I thought a quick trip to the Markarian chain would be a nice finish.  The transparency wasn’t as good anymore, and so the 9x50 finder was essentially useless.  And sweeping with the NV at the 55mm eyepiece was equally challenging as galaxies just popped up everywhere – multiples in many FoVs.  But I finally stumbled into the M-chain – with 5 obvious galaxies in the same field!  M84 and M86 shown as they always do, with very large cores, like two big eyes.  Edge-on NGC 4388 was clearly extended horizontally as the mouth.  And smaller mag 12.1 NGC 4387 was obvious, right in the middle as the nose.  I don’t recall the right eyebrow, NGC 4402 and the overlapping dimmer PGCs, but I’ll have to go back and check again.  But southeast of the mouth, mag 11.9 NGC 4413 was there to be found (core only).

 

Overall, another incredible night for me, entirely enabled with NV.  There are now years of observing I can do from the convenience of my backyard in spite of significant LP  To all you astro-NV pioneers, Thank You!!!

 

Tim


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#2 pwang99

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Posted 20 March 2018 - 12:37 AM

Galaxies with NV is definitely a mixed bag, as many have observed. (Pun unintended!)

 

Some edge-on ones are really breathtaking; the Needle and Sombrero show great extension and detail.  The smaller ones definitely need image scale.  I found that even with bright ones like M81/M82, there is something to be appreciated at both wider field and at narrower field.  Since you have a 12" objective, you should try zooming in more to M82 to study its shape.  Even with my C11 at prime focus (~100x), it was spending a little time on it, varying the gain and trying normal visual techniques to try to tease out more structure.

 

But as you saw, within the Leo and CV region, it's quite a treat just to sweep the area at wider FoV and be lost amidst all of the little galaxies.  I think the NGC 5866 triplet in Draco should be an easy target for your setup, as well: https://en.wikipedia.../NGC_5866_Group


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#3 GeezerGazer

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Posted 20 March 2018 - 12:43 PM

Really nice report Tim.  From your LP site, you might try using a 645nm or even a 685nm long pass IR filter to tease out more contrast for better NV resolution on edge on and some elliptical galaxies.  Because NV does not discriminate on the light it enhances, your LP is also getting a boost.  The long pass filters eliminate much of the visible light spectrum... domain of most LP.  So the long pass filtration can yield higher levels of contrast in the near infra-red.  If you have a #25 or #29 red filter, you can experiment with them to see if performance on your targets improves. But most IR filters are pretty reasonable in cost compared to all else associated with our NV efforts.  

 

For galaxies, I run NV unfiltered from my green zone (or darker) observing sites.  At home, a bright red zone, I either use a 5nm H-a for nebulae or 685nm IR for everything else including galaxies.  Because the spiral arms of face-on galaxies are primarily illuminated from younger stars in the blue spectrum, they are not enhanced as much through NV as red spectrum light (near infra-red) like in a galaxy core.  And, with the IR filter, there will be even less blue light permitted to pass.  But edge-ons and some ellipticals will benefit.  

 

LP varies greatly from region to region, so your results may differ or you might prefer a 610 or 645 IR filter with your equipment.  But one of the IR filters should be of help to you specifically for edge-on and some ellipticals. 

 

Looking forward to more of your reports.  I'm surprised you didn't have to be thawed out after being out long enough to engage all of your targets!  Just being able to see all of these faint friends does make the time fly, doesn't it? 


Edited by GeezerGazer, 20 March 2018 - 01:29 PM.


#4 Tim M

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Posted 20 March 2018 - 08:58 PM

Galaxies with NV is definitely a mixed bag, as many have observed. (Pun unintended!)

 

Some edge-on ones are really breathtaking; the Needle and Sombrero show great extension and detail.  The smaller ones definitely need image scale.  I found that even with bright ones like M81/M82, there is something to be appreciated at both wider field and at narrower field.  Since you have a 12" objective, you should try zooming in more to M82 to study its shape.  Even with my C11 at prime focus (~100x), it was spending a little time on it, varying the gain and trying normal visual techniques to try to tease out more structure.

 

But as you saw, within the Leo and CV region, it's quite a treat just to sweep the area at wider FoV and be lost amidst all of the little galaxies.  I think the NGC 5866 triplet in Draco should be an easy target for your setup, as well: https://en.wikipedia.../NGC_5866_Group

Thanks Peter,

Yes, I need to try increased magnification again.  On the Cocoon it seemed like I was trading scale for brightness in measures that netted zero gain.  But I will try again.  And possibly with some long pass filters as GeezerGazer recommends.

 

And that group in Draco is in the direction that is darkest for me, so I hope to give it a go next time out.  Thanks for the recommendation!

 

clear skies,

Tim


Edited by Tim M, 20 March 2018 - 09:04 PM.


#5 Tim M

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Posted 20 March 2018 - 09:02 PM

Really nice report Tim.  From your LP site, you might try using a 645nm or even a 685nm long pass IR filter to tease out more contrast for better NV resolution on edge on and some elliptical galaxies.  Because NV does not discriminate on the light it enhances, your LP is also getting a boost.  The long pass filters eliminate much of the visible light spectrum... domain of most LP.  So the long pass filtration can yield higher levels of contrast in the near infra-red.  If you have a #25 or #29 red filter, you can experiment with them to see if performance on your targets improves. But most IR filters are pretty reasonable in cost compared to all else associated with our NV efforts.  

 

For galaxies, I run NV unfiltered from my green zone (or darker) observing sites.  At home, a bright red zone, I either use a 5nm H-a for nebulae or 685nm IR for everything else including galaxies.  Because the spiral arms of face-on galaxies are primarily illuminated from younger stars in the blue spectrum, they are not enhanced as much through NV as red spectrum light (near infra-red) like in a galaxy core.  And, with the IR filter, there will be even less blue light permitted to pass.  But edge-ons and some ellipticals will benefit.  

 

LP varies greatly from region to region, so your results may differ or you might prefer a 610 or 645 IR filter with your equipment.  But one of the IR filters should be of help to you specifically for edge-on and some ellipticals. 

 

Looking forward to more of your reports.  I'm surprised you didn't have to be thawed out after being out long enough to engage all of your targets!  Just being able to see all of these faint friends does make the time fly, doesn't it? 

Yes, a 685 LP filter arrived today, just in time for the late winter blizzard and heading toward full moon.  But our local SJ star party is next month so hopefully get some dark time during spring galaxy season!  Thanks for the filter tips!

 

clear skies,

Tim


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#6 bobhen

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Posted 21 March 2018 - 07:05 AM

For seeing detail (albeit on a screen and not in real time) in galaxies, NV cannot compete with CCD or even astro-video. It’s the long exposure capability (even short 40-second exposures) of those systems that make the difference. However, you will see a lot more galaxies (and much easier) with NV than without, you just won’t see the kind of detail that those other systems with long-exposurer capability can deliver.

 

Detecting galaxy cores with maybe some surrounding haze where before there was nothing is a big step up. And remember, this is a visual pursuit not an imaging pursuit. Even in very large Dobsonians, just detecting the faint smudge of many galaxies is considered an accomplishment.

 

Also a lot of galaxies just don’t have spectacular detail anyway. Sure, the showcase galaxies do but many do not.

 

From my location and with non-assisted vision, galaxy 891 is invisible in any telescope, but it is seen as a faint slash with NV even in my small 120mm refractor. I have only detected galaxy 3628 in Leo (the edge on galaxy in the Leo Trio) once or twice in the 15-years that I had my C11 but it is visible with NV in my 120mm refractor, and on any night. However, using video, those galaxies are far more richly detailed with even a short 60-second exposure.

 

As with non-assisted visual observing, with galaxies (especially in light pollution) detection alone should be the goal, details would be icing on the cake.

 

Yes a Pass filter and larger image scale (don’t worry about fast) is a good strategy, or for more of those elusive details take out your I-Phone and snap a 10-second exposure. Those 10-seconds will make a big difference when it comes to details.

 

Bob


Edited by bobhen, 22 March 2018 - 06:02 AM.

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#7 pwang99

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Posted 21 March 2018 - 10:29 AM

I agree, bob.  Without descending down the slippery slope into the rabbit hole of "why look at images when there's APOD", I will just say that my motivation for looking through a scope is not to optimize for detail, but to partake of the whole experience of looking at the universe.  I personally feel this is true of camera-based EAA as well: as long as you can easily direct the scope and explore the cosmos, you're doing observation, in my book.

 

Along these lines, I think that one of the ineffable but real effects of using NV for galaxies is to be immersed in the view of the cosmos.  You can sweep the scope around and *see galaxies* all adrift out there.  There is a real big binary distinction between not seeing something, and seeing something.  If I want to optimize for detail, I've got a web browser.

 

I remember as a child looking at all the ovals in the Coma Berenices page of Peterson's Field Guild to the Stars and Planets.  Little arrogant ovals on a black background, the featureless "L" outline of Coma taunting me, as if to say:

 

26ua6g.jpg

 

 

Well, I've got Night Vision now... You can recede at 0.9c but you can't hide!


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#8 bobhen

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Posted 22 March 2018 - 05:59 AM

I agree, bob.  Without descending down the slippery slope into the rabbit hole of "why look at images when there's APOD", I will just say that my motivation for looking through a scope is not to optimize for detail, but to partake of the whole experience of looking at the universe.  I personally feel this is true of camera-based EAA as well: as long as you can easily direct the scope and explore the cosmos, you're doing observation, in my book.

 

Along these lines, I think that one of the ineffable but real effects of using NV for galaxies is to be immersed in the view of the cosmos.  You can sweep the scope around and *see galaxies* all adrift out there.  There is a real big binary distinction between not seeing something, and seeing something.  If I want to optimize for detail, I've got a web browser.

 

I remember as a child looking at all the ovals in the Coma Berenices page of Peterson's Field Guild to the Stars and Planets.  Little arrogant ovals on a black background, the featureless "L" outline of Coma taunting me, as if to say:

 

26ua6g.jpg

 

 

Well, I've got Night Vision now... You can recede at 0.9c but you can't hide!

Yup.

 

I still have my over-40-yearl-old copy of Peterson's Field Guild to the Stars and Planets.

 

Bob



#9 daslolo

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Posted 22 January 2020 - 10:04 PM

I agree, bob.  Without descending down the slippery slope into the rabbit hole of "why look at images when there's APOD", I will just say that my motivation for looking through a scope is not to optimize for detail, but to partake of the whole experience of looking at the universe.  I personally feel this is true of camera-based EAA as well: as long as you can easily direct the scope and explore the cosmos, you're doing observation, in my book.

Feeling one with the universe. Big motivation for direct observation.

 

How much does the optic quality matter when using NV? I mean the resolution is pretty low isn't it, and they're monochromatic so shouldn't matter much.

 

Segway: how much photoshopping goes into these APOD?



#10 Jeff Morgan

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Posted 22 January 2020 - 11:10 PM

How much does the optic quality matter when using NV? I mean the resolution is pretty low isn't it, and they're monochromatic so shouldn't matter much.

 

About 3x better than relying on averted vision.



#11 daslolo

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Posted 22 January 2020 - 11:24 PM

About 3x better than relying on averted vision.

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#12 Eddgie

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Posted 23 January 2020 - 08:50 AM

Feeling one with the universe. Big motivation for direct observation.

 

How much does the optic quality matter when using NV? I mean the resolution is pretty low isn't it, and they're monochromatic so shouldn't matter much.

 

Segway: how much photoshopping goes into these APOD?

Resolution of the best modern tubes is 72 line pair per millimeter.

 

That is probably that equates out to 2500 x 2500 lines on an LCD display.  That is actually pretty high I think, an far higher than the scotopic eye!!!! 

 

1x View of NA and Gamma Cygni complex. If you look carefully, you can even see the Veil Nebula! Credit to Cnoct for this fabulous picture.

 

Gamma Cygin by Cnoct.jpg

 

Orion at 64 lines, which is the minimum that all later Gen 3 tubes can do, and once again, the resolution here is better than the scotopic eye can see but in this case, the image is so bright, I would put it in the mesopic range, and the human eye can just resolve 64 line pair when the eye is mesopic.  It should be no surprise that NV has a minimum of 64 line pair. 

 

F9800VG on M42.jpg

 

People constantly express the thought that Gen 3 is low res, but it was designed to have better resolution than the dark adapted eye. You will probably never see more detail in a glass eyepiece because your eye is not as good as the image intensifier is.  


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#13 Astrojedi

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Posted 23 January 2020 - 04:55 PM

Great report Tim. While nebulae are stunning with NV, I have found galaxies to be a mixed bag with NV (relatively speaking). You seem to have had more success than me from my 18.5 sqm backyard.

 

Try using filters. When I first got my NV device I tried a LP filter but it was no better than a cheapo IR pass filter (630nm+). It made sense once I realized that NV sensitivity is highest towards the red end of the spectrum. 

 

I find that using a IR pass filter helps with definition / detail on some galaxies but dims the view. But always worth a try.




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