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Saturn's Polar Polygon: Sept 19 2019 @ 19:22UT, Wexford, Ireland

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#1 kevinbreen

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Posted 20 September 2019 - 05:48 AM

Well, it definitely doesn't look circular like in most of my Saturn captures, in fact it looks positively polygonal. Which is nice.

Seeing was great but rapidly deteriorated - this is the first capture taken 40 minutes after sundown.

Best 2367 frames of 9492 from a six minute capture at 26 fps.

 

Saturn 19 Sept 2019 (2).jpg

 

Light-path

Sun to Saturn to CPC1100 to IR cut filter to ZWO ADC to 1.5x Barlow to ZWO ASI224MC

 

Processing

Autostakkert!3 to Fitswork to Registax to Lightroom.

 

Planet Elevation

15 degrees


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#2 BQ Octantis

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Posted 20 September 2019 - 05:55 AM

Nice!



#3 CosmicDave

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Posted 20 September 2019 - 06:09 AM

Nice work.  Lots of ring structure, not oversharpened. Cassini gap looks perfect in size. 

 

Dave 



#4 aeroman4907

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Posted 20 September 2019 - 07:07 AM

Nicely done Kevin!  Color overall is nice, but the coloration on the rings make me wonder if your ADC was tuned correctly.  15 degrees is pretty brutal and I have never attempted imaging that low.  Overall I like the image.

 

Happy to hear that you had some great seeing, even if it did deteriorate rapidly.  That makes me spot on with my interpretation of windy.com!  shocked.gif bigshock.gif jawdrop.gif jump.gif 

Unfortunately, I can equally predict my seeing for the end of this whole lunar cycle - horrible and useless! foreheadslap.gif  Not fun since the moon is finally at a good elevation to capture images during the waning phase.  Another month to let my telescope gather dust.bawling.gif 


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#5 kevinbreen

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Posted 20 September 2019 - 07:14 AM

Nicely done Kevin! Color overall is nice, but the coloration on the rings make me wonder if your ADC was tuned correctly. 15 degrees is pretty brutal and I have never attempted imaging that low. Overall I like the image.

Happy to hear that you had some great seeing, even if it did deteriorate rapidly. That makes me spot on with my interpretation of windy.com! shocked.gif bigshock.gif jawdrop.gif jump.gif
Unfortunately, I can equally predict my seeing for the end of this whole lunar cycle - horrible and useless! foreheadslap.gif Not fun since the moon is finally at a good elevation to capture images during the waning phase. Another month to let my telescope gather dust.bawling.gif


Thanks Steve.
The ADC setting was fine. The colour of the rings is down to my incompetence in processing.

#6 happylimpet

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Posted 20 September 2019 - 08:21 AM

Belter Kevin! Great when you get good seeing at low altitude. We were in a calm central eddy of a jetstream swirl last night. I spent a while on Neptune.



#7 kevinbreen

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Posted 20 September 2019 - 08:32 AM

Belter Kevin! Great when you get good seeing at low altitude. We were in a calm central eddy of a jetstream swirl last night. I spent a while on Neptune.

Thanks Nick. What’s your appraisal of tonight’s seeing?

#8 happylimpet

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Posted 20 September 2019 - 08:54 AM

On the whole, less good. You never know though.

 

https://earth.nullsc...c=-1.404,50.921



#9 RedLionNJ

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Posted 20 September 2019 - 09:33 AM

Thanks Steve.
The ADC setting was fine. The colour of the rings is down to my incompetence in processing.

There's more (or less!) going on than self-perceived incompetence, here.

 

There should be be nothing in any processing regime which can cause the "top" area of the rings to have that peculiar color cast to them.  I agree with Steve that it looks  like an atmospheric dispersion issue.  The top parts have a "warmer" cast to them, compared to the foreground.


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#10 WicklowSkies76

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Posted 20 September 2019 - 09:42 AM

Wow Kevin - that's fantastic. You continue to give me some hope :)!



#11 WicklowSkies76

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Posted 20 September 2019 - 09:45 AM

Kevin was that a straight 6 minute capture? I've been only capturing 1,000 to 1,500 frames due to fears of rotation causing further issues with the image. Was there any de-rotation needed to be done on a 6 minute capture? I'm a bit sketchy on that process so I have avoided it.



#12 kevinbreen

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Posted 20 September 2019 - 10:09 AM

Kevin was that a straight 6 minute capture? I've been only capturing 1,000 to 1,500 frames due to fears of rotation causing further issues with the image. Was there any de-rotation needed to be done on a 6 minute capture? I'm a bit sketchy on that process so I have avoided it.

Hi Enda

I was wondering the other night if you were out imaging - the weather has been exceptionally good for this endeavour!

To answer your question - yes, it was a straight through 6 minute capture. 6 minutes is what most people would recommend, although I have had a great result with 8. What frame rate are you getting? It's been a long time since I used my Neximage 5 but from memory you should be able to get a good 20+ fps on dim Saturn with a suitably small ROI. That's not a long way from what I've been capturing at this week (owing to having to use an old laptop as my good one got water-damaged). If you've been capturing for 6 minutes and are getting 1500 frames then your frame rate is 4 fps. Surely you're not getting that?

 

For Jupiter, if you can still grab it at twilight, you should be able to get a higher frame rate as it's considerably brighter. The recommended length of capture for Jupiter is 3 mins. 


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#13 WicklowSkies76

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Posted 20 September 2019 - 10:19 AM

Hi Enda

I was wondering the other night if you were out imaging - the weather has been exceptionally good for this endeavour!

To answer your question - yes, it was a straight through 6 minute capture. 6 minutes is what most people would recommend, although I have had a great result with 8. What frame rate are you getting? It's been a long time since I used my Neximage 5 but from memory you should be able to get a good 20+ fps on dim Saturn with a suitably small ROI. That's not a long way from what I've been capturing at this week (owing to having to use an old laptop as my good one got water-damaged). If you've been capturing for 6 minutes and are getting 1500 frames then your frame rate is 4 fps. Surely you're not getting that?

 

For Jupiter, if you can still grab it at twilight, you should be able to get a higher frame rate as it's considerably brighter. The recommended length of capture for Jupiter is 3 mins. 

I was out on Monday alright. Got some nice Moon captures. Tuesday I spent mostly on Moon and Uranus. I can't get Jupiter from my location due to hills behind my house. Saturn was again a grainy result, but I don't have an ADC yet. I've only captured 1,000 odd frames at a time. I've been getting around 30fps I think. Need to capture more it seems. I was worried about rotation. Seems like I shouldn't have been. I'll give it one more try next time I get out there. I think I may have gotten into the habit of short captures because of the clouds rolling in :)


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#14 kevinbreen

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Posted 20 September 2019 - 10:26 AM

There's more (or less!) going on than self-perceived incompetence, here.

 

There should be be nothing in any processing regime which can cause the "top" area of the rings to have that peculiar color cast to them.  I agree with Steve that it looks  like an atmospheric dispersion issue.  The top parts have a "warmer" cast to them, compared to the foreground.

Before the first capture I check the ADC tuning. This was the first capture of the evening. The ADC was spot on as can be seen from this sharpened-but-not-colourized jpeg from the same tif. I was heavy-handed in my determination to get a nice yellow Saturn and in hindsight there's what appears to be some colour-bleed going on. Some things I'm good at and some things I'm not good at. Post-processing falls into the latter group.

 

2019-09-19-1922_2-KB-L_lapl4_ap20_2 - uncoloured.jpg

 

If anyone wants to have a go and make this look less anemic while preserving the rings' colour uniformity, be my guest. The only colour-processing in the above image is RGB Balance in Registax 6.

 

Below, by the way, is the colour of Saturn in the tifs that Autostakkert provides (it's a jpeg here due to size restrictions). I don't understand why it throws out a murky brown colour. This one is the deconvoluted-in-Fitswork version but the colour is identical.

 

Deconvoluted but not sharpened.jpg


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#15 kevinbreen

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Posted 20 September 2019 - 10:32 AM

I was out on Monday alright. Got some nice Moon captures. Tuesday I spent mostly on Moon and Uranus. I can't get Jupiter from my location due to hills behind my house. Saturn was again a grainy result, but I don't have an ADC yet. I've only captured 1,000 odd frames at a time. I've been getting around 30fps I think. Need to capture more it seems. I was worried about rotation. Seems like I shouldn't have been. I'll give it one more try next time I get out there. I think I may have gotten into the habit of short captures because of the clouds rolling in smile.gif

6 minutes at 30fps will bag you over 10,000 frames. You can do an RGB align in Registax by the way, did you know that? And also you can save your final image as three images, one for each of red, green and blue. The red one will be the best of the three. Give it a go tonight!



#16 kevinbreen

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Posted 20 September 2019 - 02:23 PM

On the whole, less good. You never know though.

https://earth.nullsc...c=-1.404,50.921


Nick

“less good” is a very polite way of saying atrocious.

It’s appallingly bad! I can’t even focus on Saturn. I can’t see the Cassini Division, it’s a tragedy.

Thanks for the heads-up, I think I’ll put my feet up.

#17 charotarguy

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Posted 20 September 2019 - 02:51 PM

This is an exceptional image for where you are. shocked.gif bow.gif



#18 kevinbreen

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Posted 20 September 2019 - 03:07 PM

This is an exceptional image for where you are. shocked.gif bow.gif


Thank you very much. I like to think so too.

#19 Tom Glenn

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Posted 20 September 2019 - 03:11 PM

Kevin, excellent image!  In your example of the sharpened but not processed further image, I can still detect the reddish coloration at the top of the rings, and blue at the bottom.  What criteria did you use to judge the ADC being "spot on"?  The little colored circles in Firecapture are not as accurate as compared to boosting the gain all the way to the maximum (while using the ADC mode in Firecapture), and look for color on the rings.  If the ADC is not adjusted at all, you will see a distinct "warmer" and "cooler" half of the rings.  It is very obvious.  If you then adjust the ADC until there is completely homogeneous color around the periphery of the rings, with no regional variation, then this is what I call perfect.  I usually find that if you only use the overlapping colored circles in FC, this is not sufficient to achieve the same result.  


Edited by Tom Glenn, 20 September 2019 - 03:14 PM.


#20 kevinbreen

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Posted 20 September 2019 - 03:21 PM

Kevin, excellent image! In your example of the sharpened but not processed further image, I can still detect the reddish coloration at the top of the rings, and blue at the bottom. What criteria did you use to judge the ADC being "spot on"? The little colored circles in Firecapture are not as accurate as compared to boosting the gain all the way to the maximum (while using the ADC mode in Firecapture), and look for color on the rings. If the ADC is not adjusted at all, you will see a distinct "warmer" and "cooler" half of the rings. It is very obvious. If you then adjust the ADC until there is completely homogeneous color around the periphery of the rings, with no regional variation, then this is what I call perfect. I usually find that if you only use the overlapping colored circles in FC, this is not sufficient to achieve the same result.


Hi Tom

You can actually see that??!

OK,” you live and learn”, as the saying goes. “Perfect” for me was aligning the dancing balls. I’ve just learnt something important.

Thanks 👍

#21 Tom Glenn

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Posted 20 September 2019 - 03:48 PM

Hi Tom

You can actually see that??!

OK,” you live and learn”, as the saying goes. “Perfect” for me was aligning the dancing balls. I’ve just learnt something important.

Thanks 👍

It's very subtle, and the difference becomes more apparent with further processing.  You can also see the slight color cast represented in the histograms.  If I draw a small selection around the very top and bottom of the rings in Photoshop, these are the color histograms for those regions.  You can see how there is slightly more red on the right tail of the histogram corresponding to the top of the rings, and slightly more blue at the right edge of the histogram for the bottom of the rings.  This reflects the subtle visual difference.  I find that if you use the FC ADC tool, which increases image saturation, and then adjust the gain way up, you can easily see this coloration in the live window.  Then, by adjusting the ADC to eliminate it, you can prevent this problem from happening.  But to be fair, your situation with a 15 degree elevation planet is quite difficult, and your image is very good.  

 

Top of rings:

 

histo_top.jpg

 

Bottom of rings:

 

histo_bottom.jpg



#22 aeroman4907

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Posted 20 September 2019 - 04:09 PM

Kevin, I would concur with Tom with further evaluation of your posted images that the color 'fringing' is still evident, even with less saturation.

 

Don't take this as overly critical - you have a great image of Saturn that utterly smokes mine from earlier this year, at a significantly lower elevation to boot.  A number of us know how much effort you have put forth into improving your imaging and processing and we are suggesting where those improvements can be made.  For people who aren't interested in perfecting their skills like you, I generally don't both to post anything about the images at all.

 

Keep up the great work!



#23 kevinbreen

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Posted 20 September 2019 - 04:20 PM

It's very subtle, and the difference becomes more apparent with further processing. You can also see the slight color cast represented in the histograms. If I draw a small selection around the very top and bottom of the rings in Photoshop, these are the color histograms for those regions. You can see how there is slightly more red on the right tail of the histogram corresponding to the top of the rings, and slightly more blue at the right edge of the histogram for the bottom of the rings. This reflects the subtle visual difference. I find that if you use the FC ADC tool, which increases image saturation, and then adjust the gain way up, you can easily see this coloration in the live window. Then, by adjusting the ADC to eliminate it, you can prevent this problem from happening. But to be fair, your situation with a 15 degree elevation planet is quite difficult, and your image is very good.

Top of rings:

histo_top.jpg

Bottom of rings:

histo_bottom.jpg


Wow! Thanks Tom, that’s amazing. My one concern is my ability to eyeball the difference in colour in the ADC mode of FC while over-saturating. How accurate is one’s own judgement? I mean mine..

Shame, I thought the dancing balls were definitive.

If only there was a way to analyse the histograms of the top and bottom of the planet in real time like the way you did in post.

Kevin

#24 kevinbreen

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Posted 20 September 2019 - 04:22 PM

Kevin, I would concur with Tom with further evaluation of your posted images that the color 'fringing' is still evident, even with less saturation.

Don't take this as overly critical - you have a great image of Saturn that utterly smokes mine from earlier this year, at a significantly lower elevation to boot. A number of us know how much effort you have put forth into improving your imaging and processing and we are suggesting where those improvements can be made. For people who aren't interested in perfecting their skills like you, I generally don't both to post anything about the images at all.

Keep up the great work!


Steve, I welcome all constructive criticism, thanks!

#25 Tom Glenn

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Posted 20 September 2019 - 04:33 PM

Wow! Thanks Tom, that’s amazing. My one concern is my ability to eyeball the difference in colour in the ADC mode of FC while over-saturating. How accurate is one’s own judgement? I mean mine..

Shame, I thought the dancing balls were definitive.

If only there was a way to analyse the histograms of the top and bottom of the planet in real time like the way you did in post.

Kevin

For me, if I raise the gain all the way to the max (as in literally, all the way to 600) while in ADC mode, the planet is completely blown out but with strong coloration on the top and bottom of the rings.  It's extremely obvious, like half blue, and half yellow/red.  Sorry I don't have any screen grabs to demonstrate.  But give it a try and see what you think.  


Edited by Tom Glenn, 20 September 2019 - 04:33 PM.



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