Gamma Cygni in HaSHO with RGB Stars

[wimvb]

9 hours ago, gorann said:

Well, great with someone who knows their astronomy! Would that nebula correspond to what we thought was a halo? If that is the case Rodd you have just accomplished a nice rendation of it by turning it from purple to blue, and please disregard my tweak!

https://jonrista.com/2014/09/03/the-cygnus-molecular-clouds/cygnus-sadr-reflection-nebula/

[gorann]

7 hours ago, wimvb said:

https://jonrista.com/2014/09/03/the-cygnus-molecular-clouds/cygnus-sadr-reflection-nebula/

I have now been looking at the image in that link for a while and I cannot match it up to Rodd's image. Any idea of the scale? In any case the blue reflection nebula seems to be just at one side of Sadr so it does not look like a halo.

[wimvb]

5 hours ago, gorann said:

I have now been looking at the image in that link for a while and I cannot match it up to Rodd's image.

Neither could I. I just uploaded the image to astrometry.net, and am now trying something new in PI: mosaic by coordinates, combining with Rodd's image. Never done that before ...

And no success yet ... The Rista image is only 12 x 12 arc minutes, while Rodd's image is 3 x 2.27 degrees. And there is a rotation difference of 80 degrees.

[wimvb]

I uploaded Rista's and Rodd's image to astrometry.net, and used the solved new images to create a composite. This is the result. Could it be that astrometry can't solve an image that is too small?

This is the view in the world wide telescope:

http://www.worldwidetelescope.org/webclient/default.aspx?wtml=http%3a%2f%2fwww.worldwidetelescope.org%2fwwtweb%2fShowImage.aspx%3freverseparity%3dFalse%26scale%3d2.213056%26name%3dcygnus-sadr-reflection-nebula.jpg%26imageurl%3dhttp%3a%2f%2fnova.astrometry.net%2fimage%2f5032128%26credits%3dAstrometry.net%2bUser%2b(All%2bRights%2bReserved)%26creditsUrl%3d%26ra%3d306.720790%26dec%3d40.037852%26x%3d191.6%26y%3d218.8%26rotation%3d91.89%26thumb%3dhttp%3a%2f%2fnova.astrometry.net%2fimage%2f5032128%26wtml%3dtrue#/place=Open_Collections.cygnus-sadr-reflection-nebula.jpg.0&ra=20.39052&dec=40.07633&fov=4.17508

[Rodd]

2 hours ago, wimvb said:

Neither could I.

 

8 hours ago, gorann said:

I have now been looking

Here's an updated version--better stars, more color in brightest areas, more contrast, less noise.  I mthink the reflection nebula to which you refer is that little lobe visible at about 7 oclock under Sadr.  I think that is the extent of it.

 

[gorann]

You should be very happy with producing such an outstanding image Rodd, wherever that reflection nebula is (probably at 7 oclock as you say)

[Rodd]

37 minutes ago, gorann said:

You should be very happy with producing such an outstanding image Rodd, wherever that reflection nebula is (probably at 7 oclock as you say)

Thanks Goren.   I am happy I finally was able to get it to a place I can live with.

Rodd

[gorann]

I could live with that image for a long time Rodd!

[Rodd]

20 minutes ago, gorann said:

I could live with that image for a long time Rodd!

Thanks Goren,,,,,,at least until tomorrow!

Rodd

[Rodd]

On 12/08/2018 at 08:28, gorann said:

I have now been looking at the image in that link for a while and I cannot match it up to Rodd's image.

 

18 hours ago, wimvb said:

Neither could I.

I have been thinking about the reflection nebula.  Naturally it would not be visible ina narrow band image--reflection nebula are seen in LRGB images.  So, here is the HaRGB image--mostly LRGB with Ha added to r and a bit to L.  Perhaps what I was seeing as a halo effect is the reflection nebula or at least in part?

https://www.astrobin.com/360300/H/?nc=user

[gorann]

33 minutes ago, Rodd said:

 

I have been thinking about the reflection nebula.  Naturally it would not be visible ina narrow band image--reflection nebula are seen in LRGB images.  So, here is the HaRGB image--mostly LRGB with Ha added to r and a bit to L.  Perhaps what I was seeing as a halo effect is the reflection nebula or at least in part?

https://www.astrobin.com/360300/H/?nc=user

But when you added the NB data it turned from blue to violet suggesting that you had a halo in one or more of the NB images. Have you looked for the halo in your separate NB filter images?

[Rodd]

3 minutes ago, gorann said:

But when you added the NB data it turned from blue to violet suggesting that you had a halo in one or more of the NB images. Have you looked for the halo in your separate NB filter images?

I corrected the NB image as best I can.  But the HaRGB image that I linked from Astrobin in my last post shows a blue region around sadr that looks like a refection nebula--I am wondering if that is it--or if that is haslo

Rodd

[wimvb]

I think the problem with the halo is readily solved in PS, but just for completeness, (and because I wanted to try a new idea). Here's a process that can be used in PixInsight

1. create a circular mask that reveals just the halo using PixelMath: inellips(2240, 1518, 115, 115). First I determined the center of the halo (= center of Sadr) with the cursor. Then I determined the extent of the halo, also with the cursor. I used the inellips() function of PixelMath to create the circular mask.

2. blur the mask with 20 pixels, using convolution

3. Invert the image and apply the mask

4. SCNR green at 90 %

5. This leaves the halo just a tiny bit yellow. Use CurvesTransformation to reduce the b component of L*a*b just a tiny bit (push it into the blue)

6. Remove the mask

7. invert the image

The procedure isn't optimised and really needs tweaking the parameters.

I think that the scnr procedure should be replaced by a curves transformation, so that in stead of removing the colour, it is pushed from the green into the blue-ish.

(Btw, this is from the very first image that Rodd posted in this thread)

Here's a before and after shot:

And the final image

 

[Rodd]

23 minutes ago, wimvb said:

And the final image

Yes--very nice.  I was able to come close to this--I played around with the workflow you posted from Barry and had some success.  I did not take it as far as you.  My final version was posted a while back--Not as totally free of halo as yours--but there are other aspects of the image that I think make it stronger--more blue in bright areas, less fine scale noise, more contrast throughout.   I am not inclined to try again at this point.  But, I am sure I will at some point!

Rodd

[wimvb]

5 hours ago, Rodd said:

But, I am sure I will at some point!

At least you have one more tool in your tool box. The masking method I described here can be used to minimize any circular artefact, even dust motes.

[Rodd]

6 hours ago, wimvb said:

At least you have one more tool in your tool box. The masking method I described here can be used to minimize any circular artefact, even dust motes.

So in Pixel Math you just typo in ellipse and the numbers with comas between them?  I am a little dim on the mechanics of this Pixel Math application.  I understand using the cursor so identify the pixel limits though (I think).

Rodd

[wimvb]

I can post a screen grab & the process icon later on. Am at an outing with work, atm.

[wimvb]

Here it is:

haloremoval.xpsm

Save the icons and open in pixinsight.

The PixelMath command is

inellipse(2244, 1518, 115, 115)

This function returns 1 (white) if a pixel location is within the ellipse (circle) centred at 2244, 1518 with radius 115 pixels

[Rodd]

15 hours ago, wimvb said:

Here it is:

haloremoval.xpsm

Save the icons and open in pixinsight.

The PixelMath command is

inellipse(2244, 1518, 115, 115)

This function returns 1 (white) if a pixel location is within the ellipse (circle) centred at 2244, 1518 with radius 115 pixels

Thanks Wim--I will take a look.  At preent, when I want to isolate features that do not isolate easily using the Range Mask tool, I supplement that tool with clone stamp--but that is tedious and imprecise--like trying to thread a needle with mittens on.

Rodd