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Uranus & Neptune Nov. 27th...

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#1 Kokatha man

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Posted 28 November 2019 - 06:08 AM

Nothing outstanding here - seeing was poor & made collimating difficult at the start, & transparency was an issue for the entire session but after the first Neptune capture seeing rose somewhat to what I would designate as "reasonable to good" but without good transparency which I would describe as "poor to passable." wink.gif

 

Neptune reveals nothing definite although some markings do appear to rotate, but it fails any acid test in my opinion: the same with Uranus where a darker marking "might" be rotating between the 2 frames but again nothing definite.

 

The North polar region does appear to be somewhat dark in my estimation however, supporting those who have asserted this in the current apparition...

 

Seeing was definitely better for the first part of the Uranus session after Neptune & we were emboldened to capture an r-g-b sequence: this displays that same "pinkish hue" Paolo (Baron) captured a month or two ago & is also seen on some other images such as HST etc, although I am unsure as to whether they are "true" colour images - but this was a straight r-g-b combine of a total of 9 minutes of capture data with no colour manipulation at all...

 

The seeing must've been relatively decent in that the r filter image displays the polar brightening & the darker regions South of said...other than that nothing much more except it was satisfying to at least be able to image considering all the clouds we have experienced lately...& with Uranus rising to just over 40° & imaging due North into the entire suburban glare of Adelaide at this low elevation we felt some satisfaction from our efforts. smile.gif

 

u2019-11-27_13-06_rgb_dpm.png

 

The Uranus animation below appears to require clicking on to get it to start..! ;)

 

u2019-11-27_12-47_ir_dpm.gif

 

n2019-11-27_11-22_ir_dpm.gif

 

n2019-11-27_11-47_ir_dpm.png

 

n2019-11-27_11-22_ir_dpm.gif


Edited by Kokatha man, 28 November 2019 - 06:11 AM.

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#2 Spikey131

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Posted 28 November 2019 - 06:53 AM

Cool.  Thanks for posting.



#3 RedLionNJ

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Posted 28 November 2019 - 12:22 PM

Scientifically-pleasing, as usual, Darryl,  Nice work. Particularly in less than excellent conditions you're able to show the polar brightening of Uranus is strongest in red light, as well as probable (?) features on Neptune confirmed by rotating in the right direction at the expected rate.  Can't expect much more from these targets unless conditions were A1.

 

Grant



#4 Kokatha man

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Posted 28 November 2019 - 06:15 PM

Thanks Spikey & Grant, & for all the "Likes" posted also! smile.gif

 

I don't normally drag poor old light pollution into any excuses lol.gif but on the southern tip (with a few small spaces of open land) we look through over 100km of suburbia as well as quite a lot of nearby roofs, even though Adelaide has only just over 1.3 million people.

 

This & haze makes Uranus somewhat more difficult...Neptune riding at over 50° when culminating is in much clearer air: a couple of threads (including my own comments) have already commented upon the difficulty in evincing Uranian moons, so we were lucky to even get Ariel to peep out the other night...

 

I managed to find Paolo's thread & was interested to see Christophe's (Pellier) comments re the pinkish hue, which I had seen in some HST images as mentioned above...I highly respect Christophe's Ice Giant knowledge where he complimented Paolo therein - so I guess I feel quite satisfied that we managed to pick this up in challenging conditions: interesting to note that polar brightening can be picked up using the ASI224MC colour camera (we have a website image displaying this) although one has to be careful that over-sharpening isn't fooling folks at times. (which begins at the core but can appear to make one side of Uranus disk brighter)

 

The best we (or any others I've seen) re polar brightening using the colour camera is a somewhat more illuminated NP region like the one below from 2015. (apologies for using a screenshot off my website - too hard this early in the day to find the original! lol.gif

 

But I haven't seen any colour camera images which reveal that pinkish hue btw...

 

Pat & I usually don't have much difficulty in determining the NP brightening (or what position it is in) in the onscreen feed btw...but it was good to get the red filter image to evince polar brightening (or contrast with the darker south) in the aforementioned conditions - we'd like to head north a couple of hundred kms or so for perhaps one last crack at these Ice Giants in 2019, but with the busier schedule of Xmas etc & gardening (especially raising seedlings) it might be wishful thinking! wink.gif

 

OldColourUranus2015.png


Edited by Kokatha man, 28 November 2019 - 06:17 PM.

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#5 Tulloch

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Posted 28 November 2019 - 07:36 PM

Interesting series Darryl, I've never heard of Uranus showing a "pinkish hue" before, I've only seen shades of blue/green myself however this was with my ASI224MC. I wonder whether the pink colour is not appearing in OSC cameras simply because we are not expecting to see it, and so don't colour correct the raw images to bring it up.

 

I'm going to post a new thread on this, interested in your thoughts ...

 

Andrew



#6 Kokatha man

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Posted 29 November 2019 - 07:26 PM

Interesting series Darryl, I've never heard of Uranus showing a "pinkish hue" before, I've only seen shades of blue/green myself however this was with my ASI224MC. I wonder whether the pink colour is not appearing in OSC cameras simply because we are not expecting to see it, and so don't colour correct the raw images to bring it up.

 

I'm going to post a new thread on this, interested in your thoughts ...

 

Andrew

I responded (again) to your thread a few minutes back Andrew - looking at our own again I guess my short answer to your quote above is "yes"..! :lol:

 

Also "thank you" for the additional "Likes" posted here. :)



#7 stanislas-jean

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Posted 01 December 2019 - 05:33 AM

Hi Daryl,

The pinkish hue is due to the excess of red color emitted by the planet.

I think also this effect is variable with the time.

Your rgb serie is showing well the contrast repartition between channels.

However I think the rgb principle is a little too approximative, each channel need to be balanced with the light amount of each.

Making Spectrum of the planet is a start for answering such.

So many parameters are interfering with.

 

Regarding the results, may I attach the Following, a picture done with very good characterised conditions:

http://alpo-j.asahik...19/u190916z.htm

A cap is shown, less and less appearing with the seeing conditions on degradation. The imager exhibited such very well.

 

We have such also:

uranus 20.11.19 chrisnuttal.jpg

From a british observer, I did also the similar on the same night and hour.

David Gray did also but earlier on the oppostion.

 

The cap is there.

So the question remains, and I think you know this very well, about the acquisition conditions, seeing, transparency and how to characterise them. This is a node

Also for the filtering system:

is rgb with a camera color the strict similar to color filters and a monochrome camera for same results?

 

On paper, we will have all humanity saying Indeed, but nobody exercise such "a priori" evidence.

May I suggest to image with a monochrome cam and a red fiter centered on the 619nm ray, then on the 845 ray, etc...

Then make comparison with the duly characterisation of the acquisition for each acquisition system.

 

We have until now observers showing a cap and the others showing no cap, a mimic of a hst image spreading in press news.

Not very satisfying.

I am staying still and Always on that pictures performed by the hst, Nothing to see with ours:

HST uranus 8-9nov 2014.jpg

 

Stanislas-Jean



#8 stanislas-jean

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Posted 01 December 2019 - 05:35 AM

I am sorry for the british observe, I forgot to give his name: Chrisnutall.

Now done, very sorry.

Stanislas-Jean



#9 Kokatha man

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Posted 01 December 2019 - 06:22 PM

Hi Stan! 

 

<"The pinkish hue is due to the excess of red color emitted by the planet.

I think also this effect is variable with the time.

Your rgb serie is showing well the contrast repartition between channels.

However I think the rgb principle is a little too approximative, each channel need to be balanced with the light amount of each.

Making Spectrum of the planet is a start for answering such.

So many parameters are interfering with.">

 

Not anything I'd disagree with there tbh: I know Christophe Pellier has taken Neptune spectra but I'd have to look that up to see what he might've done with Uranus...

 

Leaving aside all the influencing parameters such as seeing etc, I suspect that even with a formula for arriving at the most accurate image colour outcome there would be considerable difference between how we might arrive at the correct result using the 2 different types of cameras...

 

I did see Manolo Rodriguez' images & of course I always look at your own & David Gray's...Manolo is using an enormous length of integration (derotation) time (120" for one of them!) but as to the darker hood (which may well seem to appear or disappear) I noted above that it does appear to be evident in one of our ir610nm images, although one has to be very careful not to confuse its presence with limb darkening or over-sharpening...in the past in better situations we have regularly noted such an element.

 

Here is one of those images where I have pressed the processing more heavily...unfortunately for us Uranus is sinking lower each year & further into the light haze of Adelaide, making imaging it increasingly more difficult! frown.gif

 

u2019-11-27_12-47_ir_dpm-HP.png



#10 stanislas-jean

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Posted 02 December 2019 - 05:54 AM

Thanks for your response Darryl.

Yesterday night I had a look on Uranus Under average images but with short times of relative stability.

Regarding the pôle it didn't appear Under the seeing and well present on those time stability of few seconds.

I appeared as an extension of the limb darkening or a protusion.

For being convinced of the conditions, the 19Ari star at high magnification get the stability, mostly 5/10 unsufficient for getting Something mostly, sometimes 6-7/10 enough for.

When acquiring streams difficult to say what is globally the quality of the images. The soft is cancelling the worst ones but the indications may be just indications.

Remains also the treatment parameters, mostly kept soft for avoiding ghost/artefacts. Cannot speak about.

Also the 610nm filter that must cover the 610nm ray.

Images are R+IR, not sure that what is captured on R is the same as on IR, notably this polar cap.

If it is considered the hst set of pictures, this is effective for differences (pictures of 2014).

If on paper it seems effective the similitude between R and IR, I would say this should be experienced.

Personnally I think not that similitude actual.

Reason why I suggest the Imaging procedure with pure R filter, then pure IR filter. CCD color chipset for Nothing, the mono should be preferable, more sensitive without bayer matrix.

Stanislas-Jean



#11 Kokatha man

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Posted 02 December 2019 - 06:59 PM

...I'll integrate (derotate) the iR+R images later today to see what they reveal, the first iR capture was commenced just after UT12:42 & the R capture finished around UT13:04...which should present no issues in WinJUPOS providing I can evince Ariel from the red capture stack... ;)  



#12 Kokatha man

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Posted 03 December 2019 - 04:14 AM

Fwiw here's the r+iR integration in WinJUPOS I spoke of - nothing additional imo but "perhaps" a bit more indication of a dark region in the vicinity of the NP...my curiosity was piqued a bit by one of Stan's comment...this is a combination of Astronomiks 2c r-filter & Baader 610nm filter: from the graph I dug up the Baader iR has high transmission from just below 610nm right up into the longer iR wavelengths...here's a rough graph mock-up of these 2 filters' bandpass up to 800nm. wink.gif

 

2019-11-27-1254_4-ir+r_Web.png

 

AstronomiksLRGB&Baader610nmOverlaygraphsSmall.jpg

 

 



#13 stanislas-jean

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Posted 03 December 2019 - 06:16 AM

Thanks again Darryl for your efforts about.

However, I think we get different filter curves regarding the tricolor serie.

 

here those I own

 

astronomik-lrgb-typ2c_trans.png

 

Pay attention to R one, light transmission is between 580 to 665nm at 50% level, 600-660 at 90% level.

It covers fully the 619nm ray so proper for giving features on that wavelength without any IR and visible lights.

This is Something different.

Then for IR lights accessible to our cam may be a 742 or 807 astronomik that cover the 845nm segment is well proper.

Exposure times may be affected by these materials but this is what can be aimed anyway.

Have a look on the hst pictures serie given above where those are taken on specific wavelengthes that are characteristic of the atmosphere status.

An other approach.

The 610 filter is well proper for collecting spots or general features that cannot be attributed to specific phenomena on the moment and doesnot show what is aimed.

Good skies.

Stanislas-Jean



#14 descott12

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Posted 03 December 2019 - 01:20 PM

This is a very interesting discussion and since somebody mentioned a spectra above, I figured I would post a spectra that I captured of Uranus back on Nov 6 using the quite simple but powerful Star Analyzer grating.

 

As you can see the  methane absorptions do substantially decrease the reflection of the red wavelengths, giving both Uranus and Neptune their characteristic bluish-green color. But there are still some red wavelengths present in the spectrum  so that could be the source of the pinkish color mentioned above. The Neptune spectrum is very similar although the methane absorptions are not nearly as pronounced.

 

Since the SA is a slitless spectrograph, it captures the light from the entire disk so I don't think it would be possible to sample specific areas like the pole. That would probably take something more sophisticated like an Alpy 600.

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#15 Kokatha man

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Posted 03 December 2019 - 07:06 PM

<"However, I think we get different filter curves regarding the tricolor serie.">

 

Apologies Stan - I took the graphs off of files I keep & it appears that some time in the past I copied an incorrect graph & file-named it the Astronomik 2c...perhaps I mislabelled the Baader as the Astronomik graph..?!?blush.gif

 

I appreciate the red filter's ability to cover that wavelength & tbh utilise the (very broad) 610 filter for its apparent ability to better pick up contrast variations overall...I have also found the 570nm filter effective at times but always feel limited these days in what further we are capable of evincing from this poorly-placed planet for us...

 

However we did capture an iR742 filter image where the light throughput for a C14 is not ideal. (forgot to post it originally due to physical problems, not that much is seen...)

 

Hi Dave, you're way ahead of me on this aspect, although I have thought about a SA - I see you have the SA-100.

 

In fact so far ahead I was unaware of the Alpy lol.gif & I've just looked up Christian Buil's "review" of it  http://www.astrosurf...first_light.htm  trying to get my head around the functionality of these slit spectrographs...so much to learn, so old & so little time! wink.gif

 

I know Christophe Pellier has done some work with the SA & I've seen some of his Neptune results, but haven't looked up what he's done on Uranus: good work with that graph btw! waytogo.gif

 

ps: thanks for the folks who've "Liked" this thread also. smile.gif

 

u2019-11-27_13-22_ir742_dpm@150%_Web.png



#16 descott12

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Posted 03 December 2019 - 08:06 PM

Hey Daryl,

I am really not that far ahead at all. Just learning this stuff and it is amazing what you can learn from a spectrum. There is the SA-100 that is most commonly used and also the SA-200

https://store.fieldt...ser-100-grating

 

They are so incredibly simple to use. They look just like a 1.25 inch filter but with a  grating.

 

And there is some great software called RSpec that makes processing the spectra very easy.

https://www.rspec-astro.com

 

I found a very good reference book that has tons of spectra to compare to. Mostly about stars but it has chapters on all types of objects.

https://www.cloudyni...ence-for-newbs/

 

The Alpy 600 is a big step up from the Star Analyzer but it is amazing how much you can do with such a simple device. I don't know enough yet to know how exactly how it is better than the SA but that seems to be the logical progression from the SA ($199 USD compared to about $700).

 

You should check out the Observation Astrophysics sub-forum and you will see some great results with the SA. Also, the robin_astro user is the guru there (sort of like you in this sub-forum) so I am sure he can give you alot of good info.

 

I was hoping to capture Neptune and  Uranus tonight but so many things in life seem to get in the way....


Edited by descott12, Yesterday, 09:50 AM.


#17 stanislas-jean

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Posted Yesterday, 09:27 AM

Hi Darryl,

thanks for your response.

The 742 or 807 had been used by the italians with interresting results.

A 685 could be also a good solution helping the cam for shorter exposures.

But more interfering lights for the aim encountered.

 

What is interresting with the Spectrum of the planet is the identification of the absorption bands related to chemical elements, the relative sensitivity for each color channel, the depth of absorption band.

SJ



#18 CPellier

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Posted Yesterday, 10:26 AM

Hi Darryl and all,

Spectroscopy will be able to identify where light is absorbed, and where it is not, but as Dave says the Star Analyzer is not the good tool to identify spectral differences on the disk. The ALPY600 would be able, but another more accessible method would be to make disk-integrated photometry (so real images with photometric filters). In other words you deal less spectral resolution (much less) for an increased spatial resolution. This would be my project, weather permitted, but so far for this year I just managed over the past two nigths to take my yearly spectroscopic data for Uranus. That said, here are two results from last year on that planet, easy to read:

1) Above: reflectance spectrum (shows how the planet reflects sunlight)

2) Bottom: color spectrum (shows how the light from the planet is reaching us, whether we observe it by eye or camera)

 

u181209rp2.png


Edited by CPellier, Yesterday, 10:28 AM.

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#19 Kokatha man

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Posted Yesterday, 05:52 PM

Thanks Dave, Stan & Christophe.

 

You've jogged my memory a bit Christophe, I think we might have conversed on these subjects perhaps last year...I went to Christophe' site link https://www.planetar...trum-commented/ for a read - (a good start from anyone else looking at his post in this thread btw! wink.gif )

 

Apropos photometric filters, perhaps a specific set of some of those provided by Omega optical or other companies https://www.omegafil...page=25&page=42 might be of use therein? - but I'll leave that to you gentlemen & others, being honest...along with a few other activities there are just so many other pursuits that take up this 70-year old's time that even my passion for imaging (mainly in visible light & near iR) has waned slightly of late after a long season of Jovian imaging: I was going to target Neptune & Uranus last night but made the call early about cloud issues...even though I'd have normally set the scope up & began cooling it well before I'd made this decision  - fortunately I was correct, so I didn't get a guilty feeling had it cleared up! wink.gif




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