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Uranus & 5 moons - no rings: a warm night but no hot air!

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#1 Kokatha man

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Posted 26 December 2016 - 03:33 AM

Imaged at Sedan on 21st December in good seeing & transparency, where after spending (perhaps "wasting" :lol: ) 17 minutes on an iR850 recording after collimating, Uranus had sunk to 42° for this 10 minute capture at 70fps in iR610nm...fairly warm at over 18°C still for this capture.

 

We include as we often do nowadays the RAW stack in Registax6 with wavelets sharpening...also appended to the side of this R6 screenshot the FC .txt file: & although faint, observers will discern the N.P. collar amongst other banding as well as the full compliment of Uranus' major moons, including tiny Miranda.

 

I'm also posting my full critique of Phil & Anthony's claim to Quote: <"Positive detection of the Uranus ring"> in this thread.

With no further response to my last comments in their thread I think it polite to

allow them to let it lie so to speak, for whatever reasons...

but the matter has an important bearing on how we as amateurs should advance the integrity of

our efforts.

I refer to their images & adaptations of such, but do not post any I have made;

believing it is Phil & Anthony's sole prerogative to make public such images.

For those who bother to read the following in its entirety

our own image from 21st December 2016 - captured with

87% gain has significant relevance herein..! ;)

 

This critique is not intended to be in any way personal - but I see it as extremely important to air: & despite all 3 of us living in Australia (it is a BIG country!) we don't communicate very often.

 

I have assisted both Phil & Anthony this last year when both of them were struggling with aspects re Uranus & Neptune & had contacted me "out of the blue"...Phil on how to use the ASI224MC & Anthony in appreciating the difference between "genuine" WJ Neptune animations & those where a "skin" is created & stretched over a globe to create what one professional deems (appropriately) "movies." ;)

 

I spend an almost inordinate amount of time responding to emails etc on imaging & processing, with especial focus on Uranus & Neptune where I "think" Pat & I have established a fair reputation over the last few years...thus my passion re anything about the "Ice Giants."

 

I have no "axe to grind" with both these people whom I respect for their own planetary imaging achievements... :waytogo:

 

But I have to state that I am surprised that so many people have accepted Phil's images - processed by Anthony - as "Positive detection of the Uranus ring" to quote Anthony's website assertion.

 

This doesn't totally exclude the possibility that some indication/indicator is present...but it is an immense leap between what is produced as "evidence" & this statement of "positive detection" by Anthony.

 

On lesser notes I'm concerned that the seeing appraisal shifted from "excellent" to "perfect" over time - finding all the "reasoning" highly speculative & anecdotal with simple questions not addressed, Anthony in Posts #11 & #16 of the CN thread http://www.cloudynig...ings-of-uranus/  completely avoiding my questions.

 

My responses to his obfuscations were pretty blunt tbh - but again I emphasize that my critique is in the manner of the rigorous debate these sorts of claims should be subjected to! :poke:  :flowerred:

 

My eyes are "skeptical" as Almir Germano said when he sent me his own Uranian Ring attempts back in November for my opinion: but if we as amateurs wish to maintain any vestige of objective, professional conduct in these matters, skepticism is an essential ingredient.

 

Studying Phil's images carefully, I see NO real similarities with (eg) Bernd Gaehrken's in 2011 where the clearly illuminated ansae are defined within those areas of highly-elevated brightness.

 

Of course it was a much larger telescope (800mm) & a methane band filter was used... a similar situation with the Pic du Midi captures: however, filters & aperture aside, in essence we are asked to consider that they captured a portion of one ring ansae which even the Pic du Midi could not evince as any brighter!

 

I do "imagine" (more on this below) the faintest appearance of a brighter "arc" within the general area that could be deemed as near to one of the ansae & which does correspond with a section of the Uranus Ring Viewer's ring simulation.

 

However, there is also a darker area adjacent to the over-exposed disk at approx. the 5:30 to 7:00 o'clock positions: this tends to encourage the eye to "interpret" something in the highly-illuminated (ie amplified, scattered light) areas nearby - ie, this "arc."

 

It is, however, quite ephemeral at the very least & extremely problematical to be anything more than a "light artefact" amongst all the uneven light-scatter surrounding the disk, especially when the elevated applications required to create these aspects of the image are taken into account.

 

Carefully removing this dark, roughly semi-elliptical area virtually removes any real appearance of this element as "a faint bright arc" nearby, incidentally...

 

As well, if you look at an un-annotated 250% enlargement of their image (anyone can create this - btw, annotations can easily be visual "cues" that are equally deceptive interpreters) you will find that it is easy to "imagine" other "faint bright arcs" at various locations around Uranus' disk as well - attesting to this dark area most likely being merely a deceptive factor to assist us in imagining a faint, bright arc nearby.

 

Incidentally, this darker semi-elliptical area itself does NOT correlate with the area inside the Ring Viewer overlay btw, even though it will "rotate" in a re-orientation: it is axially displaced from those areas inside the rings for starters - & it would be extremely unlikely for such a capture to detect this even if it did correspond with that area... meaning we should reject any notion that it is objectively "real" also!

 

Quickly summarising, if we were to concentrate only on any perceived elliptical brightening to mark the actual ring detection (as per Bernd's 2011 images) as opposed to the remote likelihood of finding an actual segment of the ring ansae in the light-scatter around the planet...we would be better off considering that bright area nearer 4 o'clock - except of course that area is not commensurate with the ring ansae - & a very subjective interpretation of what is relevant suits these claims much more! ;)

 

I refuse to address the relevance of the other image subsequently "produced" following Phil's image release: Bernd's methane band 2011 image with 800mm of light-grasp is not much more definitive than this "creation" with 1/4 the light-grasp & 610nm filter...I don't believe in Father Xmas either incidentally...although I did want a "drawing set" when I was a child! ;)

 

One simple experiment that Anthony could carry out is to reprocess Phil's data for disk definition: readers might imagine that employing 36/48db gain would ruin this capture's chances of creating an image with good disk detailing (technically, good albedo variation) - but this is not so!

 

36/48db is a gain of 75%...several days ago (21/12/16) Pat & myself imaged Uranus at 87% gain (see the thread image below) where Uranus had descended to 42° (much lower than for Phil's image) in seeing we would describe as "good" (most certainly NOT "perfect" - we include the focused star from collimation as we always do, 88 Piscium in this case, to provide a gauge of the seeing)

 

Transparency was good enough for Miranda to be evinced & the darker N.T. band, the brighter EQ defined as being that brighter strip sandwiched between said N.T & the darker S.T. southern extremities of the visible disk...along with the N.P. collar that we have picked up in many of our images over the last few years.

 

All this definition we would rate as a good outcome: the image was (roughly) 30pxl in diameter (Eq) with our TeleVue barlow operating at about 1.2X to 1.3X in our variable amplification unit of the C14's imaging train.

 

Anthony, as long as you "Normalize Brightness" to around 60%-70% maximum when you re-stack the capture data you will find no problems in evincing good disk banding despite the gain used.....that is, if the data is as good as you claim, taken in "perfect" seeing & at much greater elevation than we can attain down here...& able to detect the ring system..! ;)

 

Incidentally, NO vestige of anything remotely like ansae appendages/ring detection could be evinced from our own data below...

 

Certainly an acid-test for the data you claim shows "Positive detection of the Uranus ring" (sic) to quote yourself Anthony!

 

Then again you could make the capture files or RAW stack &/or processing regimen you used available to some of us...otherwise those memories of "Cold Fusion" claims would seem more comparable!  :)

 

u2016-12-21_11-35_ir_dpm.png

 

113506_ir610_211216-Registax&FCtext.png


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#2 sfugardi

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Posted 26 December 2016 - 09:51 AM

Mo, top shelf banding! 70fps for Uranus is super fast. Quality is outstanding especially considering how late in the season it is. Congratulations on this image and thanks for posting!

Regards,
Steve

#3 Kokatha man

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Posted 26 December 2016 - 09:57 AM

...thanks for "likes" here & elsewhere as well as some private very supportive communications, they are heartening.

Nobody, & might I say especially myself, takes posting the sort of critique above lightly, because no matter how politely it is done it makes many folks uncomfortable or irritated. (& it was my intention to be courteous, notwithstanding the necessity to make some strong points)

In these circumstances I felt it imperative, most especially given that definitive "Positive detection of the Uranus ring" statement of the author.

With the evidence presented that sort of statement could not possibly be made...even if I were to believe the case had been advanced beyond a certain amount of doubt!

For the record I am always sceptical about anything more than banding on Uranus' disk, in our own images particularly - I have had certain people challenge the appearance of the N.P. collar but have never resiled from debating this with them: indeed it seems strange that some of those self-same people accept this ring detection claim on the flimsiest of evidence from a couple of questionable images...yet ignore our own & several other respected imagers' results re the N.P. collar...seemingly upon the basis that "they cannot image it."

Not sure what applying that maxim to the Uranus Ring images means :lol: but I'm happy for people to have divergent opinions on these topics - personally I'd really like to see a more open sharing of data & methodologies, particularly amongst hi-res imagers - & why I post the comments & examples I do freely with no expectations.

In any case this is not a "witch-hunt" from my perspective & not about to be turned into a continuous tirade by me...& some of the more contentious comments will not be elaborated on any further than already...I have no intention of making myself into more of a pariah on CN than I already am to some! ;)
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#4 Kokatha man

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Posted 26 December 2016 - 10:01 AM

Mo, top shelf banding! 70fps for Uranus is super fast. Quality is outstanding especially considering how late in the season it is. Congratulations on this image and thanks for posting!
Regards,
Steve


Thanks Steve - missed your post in the typing of the one above...usually CN tells me if someone has posted when I preview my own typing.

Yes, we were surprised but remember we dropped back the image scale f/l dramatically...also a lot of frames (60%+ quality) & what you see in the R6 sharpening & de-noising is all that was done in those respects despite this being a 1.5X drizzle out of AS!2 & a further 134% resize in CS4 for the final image scale of 200% of capture scale.

#5 RedLionNJ

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Posted 26 December 2016 - 04:52 PM

I'm not for one moment attempting to divert this thread from your excellent images and re-iteration of previous food-for-thought with respect to positive (aka "certain") detection of Uranus' ring system in amateur-sized instruments, but I do have a question, Darryl:

 

All this definition we would rate as a good outcome: the image was (roughly) 30pxl in diameter (Eq) with our TeleVue barlow operating at about 1.2X to 1.3X in our variable amplification unit of the C14's imaging train.

 

How do you manage to achieve such a low degree of amplification with a SCT?  Once I tack on a filter wheel, ADC and a QuickLock, I'm already up to nearly f/20, even with a so-called "1.6x" Barlow....

 

Cheers,

 

Grant



#6 Kokatha man

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Posted 26 December 2016 - 06:43 PM

Hi Grant - no worries brother...on the latter topic you mention I really don't see many people (understandably) "sticking their necks out" so to speak: I'm really an extremely sensitive soul tbh :lol:  - I'd like to think at 67 I have a handle on aspects of "social lubrication" for want of a better word where the need to maintain the appearance of harmony & friendly, cordial relationships often over-rides other issues...& I agree this is an important cohesive element: I am who I am however & on some issues I feel the importance of truth over-rides the fear of offending someone, especially when it isn't the person who is being assailed at all...just their mindset or assumptions... 

 

In fact it isn't necessarily a diametrically opposing point of view...more an attempt to tease out a discussion, but always based upon mutual respect that flows both ways without one party presuming some position of omniscience...rather hard however when you cannot get an honest exchange unfortunately...in this case the irrelevance of regurgitating commonly-understood alignment procedures...or the nonsense about rotating spider assemblies et al in response to my questions, patent obfuscation imo...

 

I would have condemned myself if I had adopted that sort of response to either of the gentlemen concerned when each had contacted me unbidden seeking clarification on planetary imaging issues... :what:

 

But enough! :lol:  <"How do you manage to achieve such a low degree of amplification with a SCT?"> 

 

You'll have to go back in time several years to http://www.cloudynig...t/#entry5306210 to look at my variable amplifier in Posts #9,10,11&12...

 

I apologise Grant but I cannot find the TeleVue graph I made by adding to it by extrapolating backwards to give an idea of the various barlows' performances at shorter distances from the lens element than that which they normally provide...with the lens element of the 2X hard up against the lip of the camera body those 1.2X to 1.3X  figures are about right...unfortunately the FC .txt is way off, as I've commented upon often: Torsten thinks it might be these planets dimness, but with very high gain that makes me unsure whether that is the sole reason... :shrug:

 

I should have stated that this last sojourn to Sedan for imaging an Ice Giant in 2016 was in part to determine what the effects of high gain produced, both from the disk perspective & possible ring detection...an advance upon our November 23rd initial trials & nothing to do with Phil's efforts I might add :lol:  - I had been corresponding with Almir Germano (Eltanin) & previously posited the use of filters different to just the methane band one... 

 

The iR850nm had shown some possibilities that came to nought - hence my comments at the start of this thread...but this is the reason for the much shorter f/l's which we reasoned would also give us very fast frame-rates for the 610nm filter to possibly help counteract the poor elevation we deal with re Uranus down here...

 

The results certainly "suggest" this ploy was at least partly successful...for the record we don't utilise the ADC & the imaging train is exactly how you see it in that old link, with the sliding camera component slid all the way inwards for minimal amplification: same setup exactly except the camera is now an ASI290MM.....back then it was an ASI120MM usb2 unit! :grin:

 

EDIT: Holy smoke - I'm a real pussycat...I've just read Pete's appraisal of Maxedout's Venus image...I'm a saint by comparison! :angel:  :rofl: 

Only joking Pete, I appreciate the thrust of your comments to Max. :grin: 


Edited by Kokatha man, 26 December 2016 - 06:55 PM.

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#7 Quaternion

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Posted 26 December 2016 - 06:56 PM

Here is a dumb question from a newbie planetary imager:

Could you "simply" take a DSO tach on imaging the rings of Uranus, by taking a LONG exposure image of Uranus? This would obviously overexpose the planet, but perhaps capture the rings. This would never work with my poorly crafted homemade EQ platform, but wouldn't your German EQ mount track well enough, if properly aligned?

...Or are the rings so dim that they don't ever get above the noise floor, even on a cooled CCD/CMOS camera? I guess in that case, you can add all the "0"'s you want, and you still won't get "1" s :-)

#8 RedLionNJ

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Posted 26 December 2016 - 08:10 PM

Here is a dumb question from a newbie planetary imager:

Could you "simply" take a DSO tach on imaging the rings of Uranus, by taking a LONG exposure image of Uranus? This would obviously overexpose the planet, but perhaps capture the rings. This would never work with my poorly crafted homemade EQ platform, but wouldn't your German EQ mount track well enough, if properly aligned?

...Or are the rings so dim that they don't ever get above the noise floor, even on a cooled CCD/CMOS camera? I guess in that case, you can add all the "0"'s you want, and you still won't get "1" s :-)

I would hazard a (fairly-educated) guess no planetary imager has a rig capable of tracking to a sub-arcsecond accuracy. It's just not necessary for 99.999% of the imaging we do. To be able to track/guide to the sort of accuracy for a single, long exposure would require an inordinate amount of cost and/or developmental effort. How many deep-sky images do you see where that degree of accuracy is mandated? Tens of thousands (even a hundred thousand plus) of individual captures are the way to go, in order to beat the seeing and take tracking/guiding accuracy into account.

 

I don't know about the likes of Darryl, Anthony and Phil (and Damian, etc.) but I'm happy to let my planet wander up to about 10 arcsec on my sensor. This really doesn't seem to have any ill-effects when we use FireCapture and AS!2 for capture/processing.

 

 

Grant

 

P.S. Darryl - I was also one of those who questioned the appearance of the ansae at 7 o'clock and not at 1 o'clock. My personal jury is still out, but I prefer to go with the US Civil Trail "guilty" verdict, where only a preponderance of evidence is necessary, unlike the criminal trial, where we need "beyond reasonable doubt" :)


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#9 Kokatha man

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Posted 26 December 2016 - 08:24 PM

Q - folks are positing various means of imaging the Uranian Ring system with smaller instruments than the 800mm scope Bernd Gaehrken successfully used with a methane band filter - & your suggestion is one of them. ;)

 

Traditional (non-cooled) planetary cameras suffer from noise problems with long exposures but that aspect shouldn't be the major concern with cooled units...

 

One issue is whether the longpass filters like the 610nm can detect this system...this is a contentious aspect but not necessarily something to reject, regardless of what I've said about others' recent efforts.*

 

As to whether a long exposure for the smaller apertures is beneficial I would speculate "yes" to the specific question - I don't see guiding as a major problem at all & with AS!2...or now AS!3...it seems these new cooled cameras are producing very good results on DSO's where extremely faint objects/detail are recorded...

 

However, a couple of things impact here...one major one being the presence of the Uranian disk & why an occulting device like Oliver's proposed coronagraph accessory would come in handy...another element is the seeing where (unfortunately!) slower acquisition rates (fps) generally coincide with poorer outcomes, especially in lesser seeing. :(

 

The beauty of the methane band filter is that it is proven to detect the rings...& planetary brightness does not over-power the image outcome where the rings are quite close to the disk at moderate image scales#...the problem is that it takes a large aperture to get enough light throughput with this filter (a very narrow bandwidth at that wavelength) & of course large scopes can achieve reasonable frame-rates & image scales...much longer wavelength, narrow-band filters are employed with adaptive optics as well for really large instruments - beyond our dreams atm, alas! :lol:

 

* The orthodox position is that Uranus' rings were discovered in 1977 during an occultation experiment where Uranus occulted a star...the starlight was attenuated several times, indicative of the ring system where the rings were blocking the starlight as well as the planetary disk itself. 

 

Plenty of links to follow on the subject & if only for a diversion read about Herschel's claims in the late 1700's..! (he who discovered Uranus & the first 2 moons detected)

 

As for their detection in longpass/near iR, apart from the issues canvassed & my "concerns" with Phil & Anthony's results my own suspicion is that this is conceivable & why I applauded their efforts regardless of my appraisals :waytogo: ....I have no doubt that others have been or are looking at "skinning the cat" re ring detection approaches.....& their efforts, like ours & Almir's etc are the only ways we will find out! 

 

# Even tiny Miranda, well outside the ring system suffers from its proximity to Uranus' disk in amateur captures: we have often been certain that we have captured its presence when elevating the image levels in a duplicated layer to pick the moons out - but Miranda is normally engulfed within the "bloat" from the planetary disk & in all these instances we reject its veracity for image inclusion.

 

On those much rarer nights when conditions conspire to allow Miranda to "pop out" well before the brightness of aforementioned disk "bloat" consumes it, we are indeed privileged & is quite often a mark of the seeing + transparency quality.....over the last few years of imaging Uranus we can count on less than 2 hands the number of images where Miranda is clearly detected - this out of well over 100 acceptable captures of the planet! 


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#10 Kokatha man

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Posted 26 December 2016 - 08:45 PM

Sorry - missed your post Grant...I agree with you about tracking & we often have a heck of a lot of that "wander." :lol:

 

I know you questioned that aspect on API Grant...my concerns are slightly wider in that the claim that a portion of the ring ansae at that position is self-evident does not pass the "acid-test" imho...in a highly-elevated area of light-scatter I see it as being more easily an artefact which deceptive cues such as the dark semi-elliptical area nearby provide, rather than an actual "detail" - & this detail (the bright arc) seems completely impossible as a finitely-defined section of the ring rather than an artefact per se: it is more easily identified as a random artefact imo - it is that folks "want" it to be a ring aspect that gives it any imprimatur as such.....

 

No other instruments (not even Bernd's 800mm) display this as a "slice of the rings" with albedo variation definition - except in those such as the Pic du Midi's methane captures...notwithstanding their actual displacement...& Marc's totally misleading attempt at a blink animation - exactly the same results as switching a light on & off in a darkened room whilst staring at it! ;)

 

The dark semi-elliptical zone is also axially mis-aligned or displaced for an "inside ansae" - not that the detection of it would be likely, regardless.

 

But sure, I understand where you are coming from & indeed your were THE only person who made any cautionary comments whatsoever...pretty sad indictment on many others tbh.....& I can see the humorous side of your Civil Vs Criminal trial analogy...heck, I don't want to hang Anthony & Phil - & the right to remain silent is a right in our justice system also..!   :rofl:


Edited by Kokatha man, 26 December 2016 - 08:47 PM.

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#11 ags55

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Posted 27 December 2016 - 09:18 PM

Darryl, your personal email to me proved what an ego maniac you are, always have to have the last word and your thinly veiled abuse is sickening. I leave you to this forum as I will not be posting here again, the Australian forum from which you were banned is a much better place for me as I never have to read your snide remarks again.



#12 Kokatha man

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Posted 27 December 2016 - 10:07 PM

Darryl, your personal email to me proved what an ego maniac you are, always have to have the last word and your thinly veiled abuse is sickening. I leave you to this forum as I will not be posting here again, the Australian forum from which you were banned is a much better place for me as I never have to read your snide remarks again.

 

Struth Phil! :shocked:  - is this the sort of response my email provoked in you, where I asked if I could publish the animation I sent to you..?!? And raising something from 6 or 7 years ago (probably more) when I had an argument with the proprietor of that forum is nothing more than insulting, irrelevant drivel intended to distract readers imho! :(  

 

I suspect the actual reality is that you could see from the detailed animation that your "results" bore no objective scrutiny whatsoever, quite clearly...I'm not interested in accepting claims that seek acknowledgement for nothing more than what I consider a very specious & "non-scientific" argument.....take a look around CN where you find people hotly disputing all manner of topics - this is an ASTRONOMY forum...not an ASTROLOGY forum!

 

I'm sorry if disputing said claims with hard evidence causes you pain...and you reckon I'm an "ego-maniac"..?!? :lol: 

 

I won't post the animation unless you change your mind btw...even though your claims were posted with the intention of full public attention/acclaim, I'll honour principles I adhere to...but if anyone asks for them as clarification privately, I see no impediments to doing so.

 

Because of the scurrilous nature of your post above, here's that (entire) email I sent you & Anthony for anyone to read btw:

 

Hi fellas - you're probably wondering why I've critiqued your efforts so vigorously...objectivity & scrupulous analysis might be one of my contrarian pedantries - or just "this is me!" ;)

I'm a sensitive soul as I said to you on API recently Anthony...but albeit passionate about many things besides planetary imaging I like to think that my baser nature is one where friendliness & compassion rule over any other responses...

This was my "cryptic" comments about "assisting you re Neptune not too long ago"...& regardless of the fact that you swapped cameras soon after Phil, you would appreciate that I was fulsome in my explanations when you asked about the 224MC last year...

When I say "cryptic" I most certainly had no intention of going into detail on the forums about our emails - thus that specific comment...but tbh when I received that email from you out of the blue I think the mildest thought I had was "****!" or somesuch...

Nobody should have had any doubts about how I created those Neptune animations, regardless of what type of pc etc they were viewing on...& the text was simple & explicit...

As I think you know, I contacted Ricardo & a couple of other people I'd sent the images to, to clarify the matter...& the immediate replies were "of course we knew, right from the start" - or somesuch...

However, as you know the worst comment I made in my first response was "I think you are labouring under some sort of misapprehension Anthony..." - & our exchange through several emails was, I think, both polite & friendly. :)

I respect you as an imager (that's R-E-S-P-E-C-T brother - not fawn ) but there are many area where we will disagree from time to time - & (quite possibly) like yourself in some areas, I believe my opinion may be better-informed!

However, & regardless of whether we disagree or not over anything I like to think that our passionate pursuit of planetary imaging should be the core focus...

To that end I would like your permission to post an animation I made a few days back from Phil's images posted on your website - that MAY or MAY NOT advance our individual perspectives which are somewhat diametrically opposed atm...

By that I mean my articulated criticism is still valid imo...but you MIGHT think that the animation supports your claims...I have to say your use of the phrase "Positive detection" still rankles me from an objective viewpoint, regardless...but that is neither here nor there in this aspect of my request imo... :)

Anyway, here it is for your perusal...I pulled it out again today hen the incessant rain down here had me stuck inside & added another frame I thought necessary...I believe it to be pretty accurate where I have delineated the "ring arc" & aligned the Uranus Ring Viewer, reducing the diagram's outline without corrupting it whatsoever to avoid the "blunt axe" approach that Marc employed in his animation...& as is often the case when aligning moons in simulations, there are slight anomalies...but tbh they are slightly more out of alignment in your own website images if the cores of each area of elevated brightness are to be accurately considered...but this is a product of several aspects & inconsequential...Ariel I deemed the prime focus for this alignment as any attempt to get all 3 roughly similar introduces errors of scale, that I'm sure I have no need to mention.

I'm very happy to contextualise the posting (if you both give permission) with something along the lines of the aforementioned <" that MAY or MAY NOT advance are individual perspectives"> in the posting...

 

Best wishes & hope you can accommodate my request herein! :) 

Darryl.



#13 eastwd

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Posted 28 December 2016 - 02:10 AM

<"How do you manage to achieve such a low degree of amplification with a SCT?"> 

 

You'll have to go back in time several years to http://www.cloudynig...t/#entry5306210 to look at my variable amplifier in Posts #9,10,11&12...

 

I apologise Grant but I cannot find the TeleVue graph I made by adding to it by extrapolating backwards to give an idea of the various barlows' performances at shorter distances from the lens element than that which they normally provide...with the lens element of the 2X hard up against the lip of the camera body those 1.2X to 1.3X  figures are about right...unfortunately the FC .txt is way off, as I've commented upon often: Torsten thinks it might be these planets dimness, but with very high gain that makes me unsure whether that is the sole reason... :shrug:

 

* * *

 

...for the record we don't utilise the ADC & the imaging train is exactly how you see it in that old link, with the sliding camera component slid all the way inwards for minimal amplification: same setup exactly except the camera is now an ASI290MM.....back then it was an ASI120MM usb2 unit! 

Hi, Darryl.  Gorgeous image in your initial post above!  Thanks for including so much detail about your setup and the settings and techniques you use with all your images.  

 

I have a couple of questions.  First, am I understanding correctly that your image above was taken at an effective focal ratio of somewhere around f/13 to f/14 (i.e., the C14's native f/11 focal ratio times a barlow magnification factor ranging from 1.2x to 1.3x)?  Second, what's your thinking on not using your ZWO ADC?  Is it only because the ADC moves your sliding custom barlow (which is wicked cool, BTW) too far from the camera focal plane to give you the relatively low magnification factors you want, or is there something about ADCs that makes you prefer not to use them at all? I'm trying to gauge whether an imaging train with an ADC next to the camera and a couple of interchangeable telecentric amplifiers of various magnifications closer to the scope that could be swapped out depending on seeing would be a good approach for planetary imaging. I welcome your insights on all this. Thanks.

 

Larry 



#14 Kokatha man

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Posted 28 December 2016 - 05:17 AM

Hi Larry - precisely the point about the ADC either extending the distance from barlow lens element to camera sensor, particularly with these smaller-pixelled sensors, but also in placing it before the EFW requires bringing the primary & secondary closer together to "throw" the focal plane further "out the tube."

 

There is a declared "sweet spot" for the image plane from the back of these SCT's...can't remember off-hand but easy to reference - & I believe the appearance of the diffraction rings when we collimated before each session was different in much earlier times when we had longer imaging trains & went past that "sweet distance" btw. :)

 

However, looking Martin's latest thread http://www.cloudynig...ations-webpage/ & reading at his own website page http://www.skyinspec...o.uk/adcs-part2 causes a major re-think of all these deliberations...for us Jupiter is the only planet that will still be (relatively) low so we will be putting into practise some of the result's of Martin's research...Uranus has really disappeared into the evening twilight & first I have to undertake a long-overdue strip-down & re-assembly of our venerable Moonlite HiRes DRO focuser before we begin imaging Jove...a few grubscrews are a tad loose after 8 years continuous service & need re-tightening... ;)

 

If I can avoid swapping gear in & out I will, but we used the ADC all the time with the ASI224MC - although its sensor pixels were somewhat larger



#15 eastwd

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Posted 28 December 2016 - 10:49 AM

Darryl, thanks for your reply and for directing me to Martin's current ADC thread.  I was searching for information on the "sweet spot" for SCTs recently, and information on Celestron units was easy to find, but information on Meade f/10 models was much tougher to come by.  A CN member quoted a distance of 3.9" (99mm) from the threads on the back end of the OTA as the optimal back focus distance for a Meade 16" ACF in this thread: http://www.cloudynig...lestron-14-c14/.  (I'd prefer for this figure to be wrong, so anyone who knows differently, please chime in.)  A decent Crayford focuser eats up about 90mm all by itself.  If you add in a filter wheel and the distance from the front of the camera to the imaging plane, then even without an ADC unit, I don't see how to avoid overshooting the sweet spot (again, assuming it really is at or in the vicinity of 99mm).  Add an ADC, a barlow or telecentric amplifier like a Powermate, and a Baader quick change adapter for convenience, and you find yourself at around 70 to 100mm beyond the sweet spot pretty quickly.  (This leads to another question re: the extent to which a barlow affects the location of the sweet spot, if at all.)  So far, I haven't been able to locate much discussion of whether and how much imaging at or near an SCT's "sweet spot" affects planetary imaging. Anyway, thanks again!


Edited by eastwd, 28 December 2016 - 11:08 AM.


#16 ch-viladrich

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Posted 28 December 2016 - 12:22 PM

Hello,

If relevant, I've run some simulations of various Barlow lenses / telescopes combinaisons here :

http://www.astrosurf...ysis-Barlow.htm



#17 neilphillips

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Posted 28 December 2016 - 03:56 PM

Lovely Uranus image Darryl.

 

The other stuff has nothing to do with me. Is a little distracting From having fun to be honest. But I realize at the top level how serious all you guys get about such things, and obviously I can see why. Though it seems a shame. A meeting of minds is not happening.

 

I think olive branches should be extended all round. To avert this bad vibe. But maybe its not for me to say. It just seems a shame to me.To extend into bad feelings. Its never a good thing, Its off putting. It never feels right. I just want to enjoy astronomy. I do think when these things happen its best privately. Just my take.  All parties that I have seen here are great amateur astronomers. All are inspiring. Bad vibe never is.

 

I know you have helped me a lot with my own imaging. So I can say that wholeheartedly.  Run ins do happen from time to time. But no one ever feels good about it in the end. Not the parties involved or anyone else I don't think.

Hopefully this can be resolved privately.

Other than that. Great work



#18 Kokatha man

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Posted 28 December 2016 - 08:09 PM

PREAMBLE: this is the last time I will address anything to do with the Uranian Ring detection claims in this thread!

 

Thanks for the image compliment Neil. :)

 

Quite simply, anyone who makes such bold claims as Anthony & Phil have should have their work open to critique & some sort of "peer review" assessment - it is, after all, a quite astounding claim to make...not "possibly" or even "to the best of our opinion" - but stated quite openly "positive detection" - or as Grant paraphrased it above means "aka certain."

 

"Breath-takingly" is how one correspondent described the level of confidence with the evidence provided...

 

The animations I created from their "evidence" debunk this assumption completely imho: there can be no reason to refuse the posting of them here but I fully appreciate CN's policy of not allowing this unless the authors give permission for me to do so. 

 

Any "stirring" in my comments has been very mild - & in the best of Australian traditions...which both fellas would encounter all the time here in Oz! ;)

 

But I should also say to you here that throughout all my posts - here & in their thread - that I have complimented their endeavours regardless of my position. :waytogo:

 

Again, quite simply, why not allow me to post the animations I've made.....if there is any reasonable doubt that my animations show nothing to contradict their claims then why prevent me from displaying them here - I can draw only one conclusion to that...if they really thought I was being what we in Australia call a "drongo" it'd be in their interest to let me make a fool of myself ! 

 

When people occasionally inform me that someone has appropriated one of Pat & my images I usually say "that's sad" because that really is an ego-motivated action...but I can understand why a lot of folks get annoyed about the "fraud" aspect of said activity...

 

In this case there is not an atom of suggestion for that sort of behaviour from Anthony or Phil - none whatsoever, full stop!

 

In their case it is simply "bad science" - or claims made on insufficient evidence imho.

 

But I'm fine about the whole situation & have no hesitation in resuming what I thought was at least mutual respect :flowerred: - the animations will be put out...because even in the amateur astronomy world, peer review appraisal & critiquing allows this to happen as long as original authorship is acknowledged.

 

I understand the sentiments you express Neil & you know I've counselled something similar myself at times ;) but this isn't a spat between 2 parties...it's a genuinely-motivated counter-argument with evidence put together with honest integrity - at one stage in compiling the sequence I thought "hang on - they could be right!" but I had made a slip-up with all the windows I had open in CS4...

 

At the time of thinking this (ie, that they could have been correct) I would have had to "bite the bullet" regardless of what I'd said previously: I would have seen that as the only proper thing to do...I'm not a politician's spin doctor who would try to weasel out, had that been my conclusion!

 

Anthony & I did exchange emails last night & I "think" we are still on cordial terms.....but it seemed like he was unaware of the other party's reaction where Phil vented further nonsense on API - so maybe we're all at logger-heads right now... :undecided:  

 

I think you're an old hippy Neil & I applaud your sentiments :flowerred:  - you know we've had some great PM's etc lately & I respect your motivations...but for goodness sake fellas, let me be allowed to post the animations here on CN as Marc seemed to be allowed to do in your thread -- for folks to make up their own minds! :)


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#19 neilphillips

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Posted 28 December 2016 - 08:58 PM

Well we know what Carl Sagan said. So it would surprise me if anyone felt differently. I may be a old hippy at heart

( did you ever listen to my guitar playing or are you more a Holst  kind of guy) But just seemed no one was talking olive branches. So thought it was worth putting that out there. I hope whatever the outcome to all this is. All parties can remain on friendly terms. Seems a shame otherwise. So good luck with that, what ever happens.

 

Btw I tried your blue tinge on top, ADC idea. And you said you was rusty. So wasn't exactly sure if the idea floated. Maybe because it was first time trying. And it was all going wrong. Jupiter flying off screen. And trying to find it again. My mount has a pin problem also, and keeps turning off grrrr 

 

But I couldn't seem to get the blue dispersion fringe on top without rotating the camera. Which didn't seem right. From reading more, if I can see the house roof directly south, inside the secondary,  and mark that on the focuser. At least I will have correct orientation when Jupiter is at culmination. If I read that correctly. Maybe I should pm instead of talking here.




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