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Jupiter gets a black eye (2019-07-16)

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#1 DMach

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Posted 17 July 2019 - 11:48 AM

Work has been unbelievably busy lately, which hasn't left much time for imaging (let alone processing).

 

I do have a backlog of data from early in July I'm still trying to get through, but I had to break with chronological order after capturing some data for Jupiter last night - the feature that I believe BQ has dubbed "the blue streak" was immediately evident during that imaging session, prominent even in the grainy raw frames coming off the sensor:

 

Jupiter 2019-07-16 15-17 v1 33pc.png

C11, ASI290MC, 2x PowerMate, UV/IR filter, ZWO ADC

 

A dark blue, almost black eddy of clouds in the turbulent wake of the GRS (to the NW of the GRS itself) ... fascinating!

 

Plenty of other interesting features are evident as well ... not least of which for me is the combination of clouds that looks for all the world like a lower case letter "a" (in the northern polar region, almost directly north of the GRS).

 

Seeing was very good for this session, the best I have seen in a while. Transparency was also excellent. Unfortunately, however, I was getting a lot of image shake due to a gusting breeze ... my mount is not usually as sensitive as that to a light wind, not quite sure what was going on there.

 

This image represents a de-rotation of 20 x 90s individual captures/stacks. I probably need to go back and reprocess this data ... looks like I've taken the sharpening a bit far and carried too much noise into the de-rotation phase.

 

Thanks for looking!

 

 

 


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#2 soldatispace

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Posted 17 July 2019 - 02:38 PM

Beautiful capture and processing! Congratulations!

Nicolas


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#3 wargrafix

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Posted 17 July 2019 - 02:54 PM

Perfection!!!


Aside from the storms, the contrast on the jovian disk is significantly less than in may. Have you felt the same?

#4 dscarpa

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Posted 17 July 2019 - 03:24 PM

 Thank for posting this as ever excellent image! Due too way too many marine layer cloudy nights here this spring and summer haven't been able to use my scopes much and other's images help fill the gap. David


Edited by dscarpa, 17 July 2019 - 03:25 PM.


#5 Tom Glenn

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Posted 17 July 2019 - 04:25 PM

Darren, another very nice Jupiter image from you, as usual.  Well done, and indeed some interesting formations!  



#6 BQ Octantis

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Posted 17 July 2019 - 04:40 PM

Very nice! And a first detailed look at what's going on. I first noticed some blue just west of the GRS on the 15th, so I poked around the posts here. The first date blue showed up in RGB was in Joe Buchanan's post on the 12th. Luke Gulliver's exquisite post on the 9th didn't show it in RGB, but his IR image showed a lot of complex activity getting churned up.

 

BQ



#7 Tulloch

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Posted 17 July 2019 - 05:50 PM

Welcome back Darren, I was wondering when you'd be back posting again, brilliant as always bow.gif .

 

With your de-rotation step, were all 20 videos continuous (ie 30 minutes of video broken up into 20 segments) or was it over a longer time period?

 

Thanks for posting,

 

Andrew



#8 DMach

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Posted 17 July 2019 - 07:28 PM

Beautiful capture and processing! Congratulations!

Nicolas


Sent from my iPhone using Tapatalk

Thanks Nicolas!

 

Perfection!!!


Aside from the storms, the contrast on the jovian disk is significantly less than in may. Have you felt the same?

Thank you! Yes, there has been a general reduction in the amount of white ammonia clouds over the season - part of a 6-7 year weather cycle on Jupiter, apparently.

 

 Thank for posting this as ever excellent image! Due too way too many marine layer cloudy nights here this spring and summer haven't been able to use my scopes much and other's images help fill the gap. David

Thanks David. I feel your pain with the clouds - it has been that way for weeks on end here lately.

 

Darren, another very nice Jupiter image from you, as usual.  Well done, and indeed some interesting formations!  

Thanks Tom!

 

Very nice! And a first detailed look at what's going on. I first noticed some blue just west of the GRS on the 15th, so I poked around the posts here. The first date blue showed up in RGB was in Joe Buchanan's post on the 12th. Luke Gulliver's exquisite post on the 9th didn't show it in RGB, but his IR image showed a lot of complex activity getting churned up.

 

BQ

Thanks BQ for the consolidated links - it's been a very interesting season for activity on Jupiter this year!

 

Welcome back Darren, I was wondering when you'd be back posting again, brilliant as always bow.gif .

 

With your de-rotation step, were all 20 videos continuous (ie 30 minutes of video broken up into 20 segments) or was it over a longer time period?

 

Thanks for posting,

 

Andrew

Thanks Andrew! Total time over the imaging session was 48 minutes - had to omit a few of the individual 90s captures as the shaking due to the wind drove the quality down, plus a few pauses to check focus etc.



#9 Vega700

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Posted 17 July 2019 - 08:29 PM

Very nice indeed and crisp details..waytogo.gif



#10 clarnibass

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Posted 18 July 2019 - 12:20 PM

Hi DMach

 

If you don't mind I have a question please. I'm trying to decide what camera to get, most likely either the ASI224MC or the ASI290MC. I see you use the latter and you have a telescope with the same F number as mine.

 

I got tons of info about what is supposedly the best ratio of F number and pixel size, what setup is better with my telescope, etc. Lots of technical info and maths. It was suggested multiple times that it's easy to get the correct setup with a x2 barlow and the ASI224 camera for f/20, but a bit more tricky to find the "correct" ratio setup for the ASI290.

 

Everything else being equal (and I'm aware that might not be the best case for both options), the ASI290 has more pixels on the target. I couldn't find an answer to what the compromise is when using the "wrong" F number for that camera. Apparently it would have more noise, etc. but that little detail of what would actually be worse in the photo seems impossible to find... in comparison with the ASI224 and "correct" setup.

 

Then I see your very good photo, using exactly that "worse" setup. The setup that has more actual pixels of the planet than if you used the 224, which would have the "correct" ratio. So you get more pixels and I guess more noise. What I'm wondering is how much better or worse the photo would have been if you had a 224 instead? What might be different about the photo itself. I'm guessing you don't have a 224 to give an exact comparison, but maybe you can shed some light on this...? Why did you choose this setup and not a different camera or a different barlow. Do you think having more pixels on the planet outweighs the compromise of the "wrong" F to pixel ratio?

 

Thank you


Edited by clarnibass, 18 July 2019 - 12:23 PM.


#11 Kokatha man

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Posted 18 July 2019 - 08:06 PM

Not too bad at all Darren - we've been cursed with a lot of cloud here lately! :(



#12 DMach

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Posted 18 July 2019 - 08:38 PM

Very nice indeed and crisp details..waytogo.gif

Thank you!

 

Hi DMach

 

If you don't mind I have a question please. I'm trying to decide what camera to get, most likely either the ASI224MC or the ASI290MC. I see you use the latter and you have a telescope with the same F number as mine.

 

I got tons of info about what is supposedly the best ratio of F number and pixel size, what setup is better with my telescope, etc. Lots of technical info and maths. It was suggested multiple times that it's easy to get the correct setup with a x2 barlow and the ASI224 camera for f/20, but a bit more tricky to find the "correct" ratio setup for the ASI290.

 

Everything else being equal (and I'm aware that might not be the best case for both options), the ASI290 has more pixels on the target. I couldn't find an answer to what the compromise is when using the "wrong" F number for that camera. Apparently it would have more noise, etc. but that little detail of what would actually be worse in the photo seems impossible to find... in comparison with the ASI224 and "correct" setup.

 

Then I see your very good photo, using exactly that "worse" setup. The setup that has more actual pixels of the planet than if you used the 224, which would have the "correct" ratio. So you get more pixels and I guess more noise. What I'm wondering is how much better or worse the photo would have been if you had a 224 instead? What might be different about the photo itself. I'm guessing you don't have a 224 to give an exact comparison, but maybe you can shed some light on this...? Why did you choose this setup and not a different camera or a different barlow. Do you think having more pixels on the planet outweighs the compromise of the "wrong" F to pixel ratio?

 

Thank you

OK, so it's time for an embarrassing admission: back when I purchased my planetary cam, I knew nothing about optimal sampling etc. ... I went purely based on tech specs plus some reviews. I then compounded the issue by buying a barlow based on it being in the 1.25" format I need plus having an optional adapter for threading directly to the camera (the PowerMate 2.5x).

 

I now know that you should ideally have an f-ratio 5x the pixel size, which would mean 2.9 x 5 = f14.5. Although according to some you can push this to 7x in good seeing, so that would be 2.9 x 7 = 20.3.

 

In hindsight, the 224MC would have been a better choice for my setup. I'm a little closer to ideal now that I have a PowerMate 2x ... assuming seeing is good, which it does generally tend to be here. Clouds are my biggest issue, which brings me to ...

 

Not too bad at all Darren - we've been cursed with a lot of cloud here lately! frown.gif

I hear and empathise with you! It has been cloudy most of the time here lately. (Although, to be fair, I haven't been around much lately to see if it was cloudy every night due to work travel.)



#13 clarnibass

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Posted 18 July 2019 - 10:47 PM

Thank you for the reply.

 

OK, so it's time for an embarrassing admission...

 

In hindsight, the 224MC would have been a better choice for my setup.

...but would it really? I mean, it would have less pixels of the planet. So the question is in what way would the final photo be better when displayed at the same size.
That's where I'm at now and and yes the 224 has the more "correct" ratio, etc.
I guess unless someone actually compared both or I buy both, I won't really know.
I haven't found the former after days of obsessive searching and the latter is not going to happen :)



#14 DMach

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Posted 19 July 2019 - 12:21 AM

Thank you for the reply.

 

...but would it really? I mean, it would have less pixels of the planet. So the question is in what way would the final photo be better when displayed at the same size.
That's where I'm at now and and yes the 224 has the more "correct" ratio, etc.
I guess unless someone actually compared both or I buy both, I won't really know.
I haven't found the former after days of obsessive searching and the latter is not going to happen smile.gif

Yup, I get that it's a tough decision without a side-by-side comparison ... but I am planning to buy a 224 at some stage, if that helps. wink.gif

 

The crux of sampling theory (as I understand it) is that the amount of detail you can resolve is limited by seeing - this is what the 5x "rule of thumb" is based on. It's all about striking a balance between signal-to-noise and resolution ... and there's some pretty solid math behind it which I'm not even going to attempt to pretend I fully understand.

 

If you undersample, you won't resolve as much detail as you potentially could have. If you oversample, you're spreading your signal/photons over more pixels, which is ultimately going to limit how many frames per second you can capture to combat the seeing in the first place. The analogy I've seen used for oversampling is enlarging a blurry image ... you don't get any more detail, you just get a larger blurry image. (And I would argue you make the blurriness more obvious this way ... you can see real-world examples where people post images at a scale/size that the data just won't support.)

 

I have done some tests for myself using a 5x PowerMate and comparing it to the 2.5x - the intent here was to leverage a concept called "oversampling and averaging" (OSA) that my company uses in the fluorescence detection devices we make, which improves the overall signal-to-noise. (The "lucky imaging" approach itself is effectively leveraging the same concept.) Important to note that I never intended to use the images at the 5x magnification - the OSA approach dictates that I would reduce the image size by 50%, to bring it back to the same scale as the more ideal 2.5x sampling (hopefully with improved signal-to-noise overall).

 

What I found in practice is that there was no significant improvement in the image ... but I did have to compromise my frame rate/gain choice. Just as the theory would suggest (funny about that)!

 

But the more relevant data point for you: when I moved from using the 2.5x PowerMate to a 2x, there was no loss of detail in my images ... if anything, they have improved! (As I'm now able to achieve my desired frame rates at lower gains = less noise.)


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