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Fireworks Galaxy NGC6946

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Terri Zittritsch
(@terri)
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The first shot I did with my Celestron 1100HD earlier this year.  I was getting a lot of mirror movement so it's back at celestron.    During most exposures, the mirror moved quite a bit as seen by stars all moving one direction.   Guiding of the mount was great.   This is also one of my first shots with a new OSC camera.  Not used to it yet and have lots of overexposed stars.  Will take another crack at this one next year.

 

This topic was modified 2 months ago by Terri Zittritsch

   
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Terri Zittritsch
(@terri)
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Tried fixing stars and think I made them worse.

 

 


   
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Paul Walker
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I think they are better.  I like the overall result much better.  Eventual the viewer may notice a few of the brightest stars look a little off due to the effort to preserve their colors.  I find no issue with images where the center of the brightest stars being completely saturated (white).  The halos will still show the star's color. It's more like the view through a telescope which may be why it happens to be my preference.

Definitely a more pleasing result.


   
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Terri Zittritsch
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Thanks Paul, i did a linear deconvolution to try to minimize the elongated stars.  I also did a separate processing of stars and galaxy which helped preserve more color.   I was disappointed to have to send the OTA back to Celestron with jupiters opposition coming up.   But it wasn’t holding collimation and the mirror movement was excessive.   I hope they can remedy it.  Costs a lot to ship that thing to California and back!

 

terri


   
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Paul Walker
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That's too bad about having to send the scope back.  I expect mirror shift is at least part of what is limiting the subs on my setup, especially when I have the 10" f4 on it. The primary locks down on the 10" but I use a small 90mm Cassegrain scope for autoguiding. It is not a high-end scope, it's primary can't be locked down so it likely shifts slowly.  I use it straight through, I never use the flip mirror.  So between the guider's primary shifting, the connecting hardware between the guide and main scope I am limited to 4 minutes subs.  I was thinking the secondary on the 10" may shift a little as well but it's a Schmidt-Newtonian so that's unlikely.  The other scope I use on the mount are Newtonian so there may be some rotation of the secondary/flexing of the spider for the secondary on those.  I don't normally see any jumps between images just a small consistent shift between images so most of the issue is likely the main scope to guide scope hardware.


   
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Greg Erianne
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Posted by: @terri

Tried fixing stars and think I made them worse.

 

 

I agree with Paul, Terri. This looks great!  Big improvement.

 

Greg


   
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Terri Zittritsch
(@terri)
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Posted by: @pwalker

That's too bad about having to send the scope back.  I expect mirror shift is at least part of what is limiting the subs on my setup, especially when I have the 10" f4 on it. The primary locks down on the 10" but I use a small 90mm Cassegrain scope for autoguiding. It is not a high-end scope, it's primary can't be locked down so it likely shifts slowly.  I use it straight through, I never use the flip mirror.  So between the guider's primary shifting, the connecting hardware between the guide and main scope I am limited to 4 minutes subs.  I was thinking the secondary on the 10" may shift a little as well but it's a Schmidt-Newtonian so that's unlikely.  The other scope I use on the mount are Newtonian so there may be some rotation of the secondary/flexing of the spider for the secondary on those.  I don't normally see any jumps between images just a small consistent shift between images so most of the issue is likely the main scope to guide scope hardware.

You know Paul, for 40" of focal length you really do not need a very long guide scope.  I'd replace that SCT guide scope with a short tube 60 to 80mm aperture scope.   PHD2 does sub-pixel guiding and the latest version uses multiple stars, so it's very accurate.    For my TEC 140 I can get away with a 240mm guide scope, although I do have a 400 mm one as well.    For the SCT I might have to resort to an OAG, which I have, but I just dread using it.    Me and OAGs haven't gotten along in the past. 

 

Terri


   
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Terri Zittritsch
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Posted by: @greg-erianne
Posted by: @terri

Tried fixing stars and think I made them worse.

 

 

I agree with Paul, Terri. This looks great!  Big improvement.

 

Greg

Thanks Greg, I do like the galaxy, but it's suffering from the same smearing as the stars.   But I did get descent color and exposure with the OSC.   I love that these new cameras have no amp glow or gradients to get rid of.    Very clean processing.


   
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Paul Walker
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Hi Terri,  On the guider suggestion, the "problem" is I'm not using a laptop or other computing device so I use a Celestron NexGuide, stand alone autoguider (has a little built-in display and plugs directly into the mount's autoguider port, no computer required (and can't be used with one).  Actually I'm using a NexGuide so I don't have to use a computer.

I have tried smaller scopes with it but it needs the 90mm aperture to get down to 6.5 or 7th mag stars for guiding.  Even then I need the "alt-az" platform I built for the guidescope to find a bright enough star to guide on.   Someday I may switch over to using a laptop.  I have one I could use.  Probably will kick myself someday for not doing that sooner.  Now that I have my observatory deck, and the way I have things set up it would be fairly easy to incorporate a laptop.  The roll off shed has a fold down shelf that's only a few feet from the scope and I can run the cable(s) from the laptop to the scope through conduit that's already in place under the decking.  I have power litterally under my feet with is piece of decking hinged for easy access (that's also where the end of the conduit is).


   
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Ron Anstey
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@terri I'm liking this.

ron


   
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Terri Zittritsch
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Posted by: @ron-anstey

@terri I'm liking this.

ron

Ron, thank you so much!   Good to see you on the forum!

 

Terri


   
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Terri Zittritsch
(@terri)
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Joined: 3 years ago
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Posted by: @pwalker

Hi Terri,  On the guider suggestion, the "problem" is I'm not using a laptop or other computing device so I use a Celestron NexGuide, stand alone autoguider (has a little built-in display and plugs directly into the mount's autoguider port, no computer required (and can't be used with one).  Actually I'm using a NexGuide so I don't have to use a computer.

I have tried smaller scopes with it but it needs the 90mm aperture to get down to 6.5 or 7th mag stars for guiding.  Even then I need the "alt-az" platform I built for the guidescope to find a bright enough star to guide on.   Someday I may switch over to using a laptop.  I have one I could use.  Probably will kick myself someday for not doing that sooner.  Now that I have my observatory deck, and the way I have things set up it would be fairly easy to incorporate a laptop.  The roll off shed has a fold down shelf that's only a few feet from the scope and I can run the cable(s) from the laptop to the scope through conduit that's already in place under the decking.  I have power litterally under my feet with is piece of decking hinged for easy access (that's also where the end of the conduit is).

I forgot about your stand alone guider setup, I understand now.     You need a makeover!    Dealing with just 6.5 or mag 7 stars must be tough!


   
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