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Dark Lanes in Rosette

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#1 Eddgie

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Posted 21 December 2017 - 10:31 AM

Peter and I met out at the dam last night and did some observing and saw a lot of fantastic stuff, but one of the best of the night for me was spotting three dark lanes in the Rosette Nebula.

Conditions were fairly good (SQM Meter is on my Christmas Wish List) with naked eye visibility maybe down to 4.5 to 5 near zenith, which is as good as it gets for us at Mansfield dam.

 

We used Peter's 16" f/ 4.5 and were doing afocal so probably working at about f/2.7 to f/2.5.  I have of course studied Rosette multiple times in the 6" at f/2.8, but that scope does not have the image scale for this particular observation.  

 

I don't know for sure if we were using 41mm Pan or 55mm Plossl, but Rosette was large and what catches the eye most is the scallops that we interpret as the petals of the rose.  Peter was captivated by the dark void at the center, but I was looking more at the structure in the nebula itself.

 

There is a bright condensation that forms a kind of bowl shape with the top facing into the core stars. This condensation is on the same side of the nebula as the star 13 Mon.  With some study, I was able to actually pick out some of the small lanes that are often shown on long exposure images.  This was the first time I have seen this kind of structure in the Rosette and it adds a whole new feeling to this target.  There are three very dark lanes but they are tiny at this scale.  Eager to show Peter, I did not spend a lot of time on these and I had to kind of guide Peter with verbal description to them, but once he saw them and knew the scale of what he was looking for, he was able to pick out the other too.

 

Today when I looked at pictures, I could see that I did not follow these lanes out as far as they go, and one in particular looks to be worthy of further study.. In pictures, this one shows as a "Y" shape, and this one was the first one I came to and I think most conspicuous because it is very straight, on the end pointing into the void, and the human eye excels at picking out straight lines because this is where it sees the best contrast (and this is why I suppose optics test charts tend to use straight lines).   Now, I did not take the time to study it out because the next dark land caught my attention first, but had I done so, I think it might have been possible to see the rest of the Y, though I only observed this one leg last night.   The next dark nebula is not a lane, but more of a little comma shaped inclusion.  It is not as long and the shape makes it appear less sharp, but it was easy to see now that my eye was looking for detail in this size range.  It is short and wide, but again, if you are looking for dark nebula that has about the same size as the width of the lane in the "Y" shaped dark lane, it is easy to spot.  Once I guided Peter verbally to the "Y", and told him where to look for the others, he spotted them right away. 

 

The last one shows as much more complex in pictures, but once again, the eye does not see a jagged line as easily as a strait line, and there is only one part of this complex dark lane that stood out to me, and in eagerness to get Peter to the eyepiece, I did not spend a lot of time on this one either.  Peter and I are easily distracted by shiny things, and I supposed something else caught our attention, so I did not get back to these, and I regret that, but there will be other nights. 

 

Included is a Sky Safari capture that shows these lanes well and I am annotating them to show the ones we actually saw and what parts of them I can report as having seen with very good authority, but in the 16" f/4.5 working afocally, these are very small so be aware of that and carefully work your way though this little bowl shaped part of the nebula and my guess is that with 12 to 14", working between f/3 and f/4, with care, you should be able to pick them up, though I don't know how far you would be able to follow them, but that is why I am writing.  They can be seen, and my guess is that with dark skies, a considerable amount of detail in these lanes could be presented to you.  

 

Again, I think that that with careful study, it might be possible to follow these lanes out much further, but once you know where to look and know that the scale of these is really small, I think it is possible to see them.  A good guide would be that if you can resolve some of the dark lane in the Eagle, you might be able to get these, but I think you need a larger scope working at an effective focal ratio maybe in the f/3 range is best bet, so afocal my be required.

 

Fantastic to see these.   Don't get lost in the bigger petal scallops (easy to do) and miss these really fantastic little dark lanes!

 

Enjoy!

 

Rosette annotated.jpg

 


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#2 Eddgie

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Posted 21 December 2017 - 10:38 AM

The one to the lower left was the one that was most easily seen.  As you can see, it is a longish, straight-ish feature, and the eye will pick this out easier than the others, but once you see it, this will calibrate your sense of scale and I think make the others much quicker to pick up.  Once Peter caught this one, he spotted the others with very little effort.

 

Have an epic day! 


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#3 Eddgie

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Posted 21 December 2017 - 10:43 AM

And I have to say..... Not bad at all for a "Category 1" causal observer, eh?  lol.gif lol.gif lol.gif

 

 

 

 

 

 

 

Sorry, I could not resist that.   waytogo.gif


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#4 pwang99

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Posted 21 December 2017 - 11:57 AM

Heh.. Yeah that dark lane was the most prominent.  I believe we were using the 41mm Pan, and FWIW the scope is an f/4 and not f/4.5.

 

For me, several highlights last night were:

- binoviewing M42 and M43, with the white phosphor PVS-7 at prime focus in my TOA-130, with a 0.7x reducer

- seeing Flame unfiltered with the Mod3 

- the pronounced, filamentary structure of M43 that shows up unfiltered in the Mod3.  I would recommend everyone to check out M43 with and without filters, if they are under somewhat dark and transparent skies.

 

After you left, Ed, I did some more 5x viewing with the Mod3.  The skies were much more transparent at 2am, although I had to turn on the van and use the heater to dry dew off my filters.  Flaming Star in Auriga is a marvelous sight at 5x.  At 2am, the 1x view of the entire Auriga / Gemini / Orion region was really, really splendid.  Looked like a dimmer version of the MDW survey picture.  The Seagull was positively bright, and Heart and Soul were shining.  I was cold and exhausted but it was worth it!!

 

I also have to say that after we did the aviator tube vs. L3 filmless comparison on the Double Cluster, I actually enjoyed the "naked glass" view the best, at least through the 16".  For brighter open clusters, the sharpness of naked glass still has a unique aesthetic quality.


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#5 Eddgie

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Posted 21 December 2017 - 01:28 PM

When conditions permit and I am working on stellar targets, I go without filters.  I just think I can go deeper when no filter is used..

 

Even under light pollution, in the slower f/4.9 dob, I often run unfiltered except for nebula.  Sometimes I use the 610nm and sometimes 650nm, but I don't like going to a longer cut than this because it kills nebula.

 

I did enjoy the 5x.  It really did a great job with Heart and California.   Lots of detail in California at 5x and with this big a field, you can see the extension that goes pretty far outside of the classically drawn boundaries. 

 

I noticed that on M42, the 5x also did a great job on this nebula unfiltered.

One of my great regrets and a major shortcoming of the full binocular is that I can't use lenses like the 5x.   Amazing what I can see at 3x, but sometimes having a 40% increase in scale would be most welcome.


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#6 Jeff Morgan

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Posted 21 December 2017 - 05:08 PM

And I have to say..... Not bad at all for a "Category 1" causal observer, eh?  lol.gif lol.gif lol.gif

 

 

 

 

 

 

 

Sorry, I could not resist that.   waytogo.gif

 

The person who came up with that sweeping generalization is appropriately described as a Caveman.


Edited by Jeff Morgan, 21 December 2017 - 05:09 PM.

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#7 NochesNubladas

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Posted 21 December 2017 - 05:22 PM

When conditions permit and I am working on stellar targets, I go without filters.  I just think I can go deeper when no filter is used..

 

Even under light pollution, in the slower f/4.9 dob, I often run unfiltered except for nebula.  Sometimes I use the 610nm and sometimes 650nm, but I don't like going to a longer cut than this because it kills nebula.

 

I did enjoy the 5x.  It really did a great job with Heart and California.   Lots of detail in California at 5x and with this big a field, you can see the extension that goes pretty far outside of the classically drawn boundaries. 

 

I noticed that on M42, the 5x also did a great job on this nebula unfiltered.

One of my great regrets and a major shortcoming of the full binocular is that I can't use lenses like the 5x.   Amazing what I can see at 3x, but sometimes having a 40% increase in scale would be most welcome.

Exactly how I feel about my nebula filter. It degrades everything but a nebula.



#8 Phil Cowell

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Posted 21 December 2017 - 07:57 PM

 

And I have to say..... Not bad at all for a "Category 1" causal observer, eh?  lol.gif lol.gif lol.gif

 

 

 

 

 

 

 

Sorry, I could not resist that.   waytogo.gif

 

The person who came up with that sweeping generalization is appropriately described as a Caveman.

 

I will bite my tongue, I will bite my tongue lol. 


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#9 moshen

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Posted 22 December 2017 - 03:56 PM

Nice observing report! I am curious if you notice a difference between the .1EBI and .6EBI tubes that I believe you guys mentioned you had. 

I know Eddgie mentioned the slightly higher SNR on Peters tube was subtly noticeable but wondering if the lower EBI on Eddgie's tube was ever noticeable..



#10 jdbastro

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Posted 22 December 2017 - 08:42 PM

Here's a still of the same region within the Rosette shot using a 120mm/f7.5 refractor (Tak TSA 120) and a WP unfilimed intensifier:

 

RosetteNeb TakTsa120 30sec 200iso 12nmHalpha
 
I don't recall whether the dark lanes are visible in real-time with this scope.

 


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#11 Eddgie

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Posted 22 December 2017 - 09:01 PM

I don't think we looked at any nebula that was dim enough to really make a good comparison.

 

As I understand it, the EBI sets the absolute floor on the brightness that would be required for a detail to be perceived.  In theory this means that if both of the units had the same gain and were used on a very dim target, the signal from the tube with lower EBI would stand our better from EBI caused glow in the view but I guess you would have to find one that was just between the EBI thresholds to see this.   That would be luck I think. 

 

We were all over the place with what we were using though so we were not really looking to do this kind of comparison. Between the two of us, we had probably 7 or 8 individual tubes (I had two Mod-3s from the binocular, the Micro, and a PVS-7 B, Peter had two Mod 3s a PVS-7 Charlie with the WP, and maybe he had his PVS-7 Baker, I don't know, but to be honest, it was pretty sinful that between us, we had enough NV gear to buy a nicely optioned new compact sedan. 

 

So, totally were not doing threshold comparisons.  We just used whatever one of us had in our hand at the moment and just enjoying what we could see. 



#12 Eddgie

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Posted 22 December 2017 - 09:07 PM

Jay, you are a winner!

 

Nice catch!

 

I could not see the full "Y" shape on the nebula at the left on the image, but I have to confess that I got distracted by the two nebula above and right of that one, and quickly urged Peter to see them.  When I looked again, I of course kept looking around the diameter of the loop for more nebula and just did not make it back to look more closely at the Y.

 

They were absolutely visible though, but I think you need some aperture to get the scale and some speed to get the brightness. 

 

As always, another fantastic shot!

 

(I did have the discussion with Peter that next time we go, we need to have some structure to target selection.  We are just like kids in a bounce house.)


Edited by Eddgie, 22 December 2017 - 09:13 PM.


#13 GeezerGazer

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Posted 23 December 2017 - 07:32 PM

Ahhh, Rosette... one of my very favorites.  Really a great photo Jay!  bow.gif   I don't remember seeing the Y in my 140 visually... I did see lots of "petals" and most of the central stars though.  Very beautiful visually with NV.   I'll be looking at this again in January and searching for the Y.  Thanks Ed, nice report. waytogo.gif



#14 Jeff Morgan

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Posted 23 December 2017 - 09:12 PM

Ahhh, Rosette... one of my very favorites.  Really a great photo Jay!  bow.gif   I don't remember seeing the Y in my 140 visually... I did see lots of "petals" and most of the central stars though.  Very beautiful visually with NV.   I'll be looking at this again in January and searching for the Y.  Thanks Ed, nice report. waytogo.gif

 

The Rosette is awesome with NV.

 

At 1x, to my eye it appears as the brightest large nebula in the winter sky from Cassiopeia to Puppis.



#15 guangtou

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Posted 24 December 2017 - 10:50 AM

Heh.. Yeah that dark lane was the most prominent.  I believe we were using the 41mm Pan, and FWIW the scope is an f/4 and not f/4.5.

 

For me, several highlights last night were:

- binoviewing M42 and M43, with the white phosphor PVS-7 at prime focus in my TOA-130, with a 0.7x reducer

- seeing Flame unfiltered with the Mod3 

- the pronounced, filamentary structure of M43 that shows up unfiltered in the Mod3.  I would recommend everyone to check out M43 with and without filters, if they are under somewhat dark and transparent skies.

 

After you left, Ed, I did some more 5x viewing with the Mod3.  The skies were much more transparent at 2am, although I had to turn on the van and use the heater to dry dew off my filters.  Flaming Star in Auriga is a marvelous sight at 5x.  At 2am, the 1x view of the entire Auriga / Gemini / Orion region was really, really splendid.  Looked like a dimmer version of the MDW survey picture.  The Seagull was positively bright, and Heart and Soul were shining.  I was cold and exhausted but it was worth it!!

 

I also have to say that after we did the aviator tube vs. L3 filmless comparison on the Double Cluster, I actually enjoyed the "naked glass" view the best, at least through the 16".  For brighter open clusters, the sharpness of naked glass still has a unique aesthetic quality.

Peter,

 

Do you prefer the 41mm Panoptic over the 55mm Plossl for afocal?


Edited by guangtou, 24 December 2017 - 10:51 AM.


#16 pwang99

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Posted 28 December 2017 - 01:16 PM

Yes, I prefer the 41mm Pan because in my scope, the 55mm only barely comes to focus and with an MPCC, there is really bad coma.  The 41mm shows no such issues and provides a fine image scale for most things.

 

I need to get the shorter truss poles set up on the scope and then maybe the 55mm will work better.


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