Return to the Cloudy Nights Telescope Reviews home page


Observing >> Solar System Observing

Pages: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | (show all)
azure1961p
Postmaster
*****

Reged: 01/17/09

Loc: USA
Re: Uranus cloud bands in a C8 new [Re: Asbytec]
      #5495460 - 10/29/12 10:43 PM

Norme those Uranian festoons in the Keck images are wild. Its a hellish looking place despite the poker face it presents visually. Those festoons are so incredibly even and symmetrical.

Pete


Post Extras: Print Post   Remind Me!   Notify Moderator  
Rick Woods
Postmaster
*****

Reged: 01/27/05

Loc: Inner Solar System
Re: Uranus cloud bands in a C8 new [Re: Cotts]
      #5495496 - 10/29/12 11:06 PM

Quote:

Stan, your drawings do not show the same curvature of the features as they are in the Keck pictures. In most of your sketches you show the 'bands' to be nearly straight lines and never even remotely as curved as they are in reality. This, plus your continiung failure to show the limb darkening in your sketches, reduces greatly the credibility of your efforts.

Dave




Dave, I don't agree. Stan's belts appear to me to be curving in the same general way as the Keck pictures. Naturally they're not a perfect match; this is a very difficult observation at best. And, Stan has already said he deliberately doesn't include the limb darkening. I don't understand why that's such a big deal.
Can't anyone accept his observations for what they are - his observations? A couple of others have reported seeing features on Uranus without getting the treatment Stan is getting here.
God help him if he ever reports using Brandons!


Post Extras: Print Post   Remind Me!   Notify Moderator  
Cotts
Just Wondering
*****

Reged: 10/10/05

Loc: Toronto, Ontario
Re: Uranus cloud bands in a C8 new [Re: Rick Woods]
      #5495519 - 10/29/12 11:15 PM Attachment (35 downloads)

Here's a screen grab of a typical Stan rendering of the belts/zones on Uranus. There's virtually zero curvature....

Post Extras: Print Post   Remind Me!   Notify Moderator  
Cotts
Just Wondering
*****

Reged: 10/10/05

Loc: Toronto, Ontario
Re: Uranus cloud bands in a C8 new [Re: Cotts]
      #5495528 - 10/29/12 11:19 PM Attachment (30 downloads)

And here's a screen grab of the Keck IR shot which shows the amount of curvature that should be there assuming the bands/zones Stan is drawing are parallel to the equator of Uranus which they pretty much must be...

No resemblance.


Post Extras: Print Post   Remind Me!   Notify Moderator  
starrancher
Carpal Tunnel
*****

Reged: 06/09/09

Loc: Northern Arizona
Re: Uranus cloud bands in a C8 new [Re: Cotts]
      #5495551 - 10/29/12 11:36 PM

Think there might be a slight difference in a Keck IR shot and what can be detected with a backyard scope through an eyepiece .
Seems some just need someone to bash and hate all the time .


Post Extras: Print Post   Remind Me!   Notify Moderator  
Asbytec
Guy in a furry hat
*****

Reged: 08/08/07

Loc: La Union, PI
Re: Uranus cloud bands in a C8 new [Re: starrancher]
      #5495650 - 10/30/12 01:03 AM

Pete, hellish, yea....but I would give my left nut (since I don't use it much, anymore) to go there. Heck, to see it that well.

Personally, I cannot account for the differences between keck at 1.6 micrometers and visual at the limit of the human eye.

If anyone can see bands on Uranus, it's an amazing thing. An amazing, rare ability. So many simply cannot, myself included. Best I can make out is limb darkening and some tricky, random albedo changes probably induced by seeing...and trying and really wanting to see bands on Uranus.


Post Extras: Print Post   Remind Me!   Notify Moderator  
stanislas-jean
Carpal Tunnel


Reged: 10/22/08

Re: Uranus cloud bands in a C8 new [Re: Asbytec]
      #5495719 - 10/30/12 02:50 AM

I donot understand why people doesnot go to the spectrum given at the begin or the middle of this forum where the possible methane absorption bands appears, in visual field and NIR field with an evaluation of the possible contrast level. That's it. This is more constructive than intellectual observations (Pete) or by strict comparison (feature to feature with Cotts). All are not on the needed wave.
Curvature of banding system, you are too demanding with regards the kind of views we have. I remind here that most of the imagers happy to report banding system shows straight bands also (see the alpo japanese site). We report what we see and it is needed big apparent sizes observed for collecting such apart around the pole that is more evident.
The documents that you see on the forum are performed directly from the eyepiece, they are raw data not improved after at the desk, so some "features" may appear resulting of the paper surface quality or a pen a little too pushed.
We are at an epoch where avery thing must be perfect where this is not possible and not existing.
Festons on the sketch, I never wrote this word, never, this is your imagination that read, not your eyes.
Everything is difficult to collect and the sketch you remind, Cotts, is may be the better one that i did on Uranus and easily performed with excellent sky conditions.
Frankly it stuns me still, after I saw the keck images.
A new time, Images in IR will not be quite the same even with the similar resolution level in visual field (essentially the R channel). Because the interrested atmosphere layers in each are not the same because the atmosphere is scattering the light also.
A new time nobody is able to catch light above say 0.7Ám, for convincing you, if this is not done, you can heat a piece of steel at different temperature and test your eyes, you will see. This is not a matter of superhumans but matter of training and lot lot lot of tests. Did you test yourself? Did you test the pertinence of your observational method (even imagers)?
I think not.
Stanislas-Jean


Post Extras: Print Post   Remind Me!   Notify Moderator  
Cotts
Just Wondering
*****

Reged: 10/10/05

Loc: Toronto, Ontario
Re: Uranus cloud bands in a C8 new [Re: starrancher]
      #5495896 - 10/30/12 09:06 AM

I was referring to the curvature only. I know the detail in the Keck images would not be visible to Stan. My point is his ignoring this curvature (which would be in any bands parallel to Uranus's equator) in his sketches.

Dave


Post Extras: Print Post   Remind Me!   Notify Moderator  
telescopemullet
professor emeritus
****

Reged: 11/16/09

Re: Uranus cloud bands in a C8 new [Re: Cotts]
      #5496024 - 10/30/12 11:00 AM

There's no hate going on here. He is posting drawings and touts them as being "real." Others can post that what he is drawing is imaginary. That's not hating; it's posting an informed and rationale difference of opinion, which just happens to be well cemented in fact.

Post Extras: Print Post   Remind Me!   Notify Moderator  
stanislas-jean
Carpal Tunnel


Reged: 10/22/08

Re: Uranus cloud bands in a C8 new [Re: telescopemullet]
      #5496060 - 10/30/12 11:37 AM

without any argument.
just free opinions.
Stanislas-Jean


Post Extras: Print Post   Remind Me!   Notify Moderator  
stanislas-jean
Carpal Tunnel


Reged: 10/22/08

Re: Uranus cloud bands in a C8 new [Re: Cotts]
      #5496076 - 10/30/12 11:51 AM

Cotts, you should consider the fact that at the eyepiece the apparent size of the planet stands between 20 and 26 minuts of arc only for me and my means. We need 500x to catch Uranus with the same size as the moon viewed with the nake eye.
Try to do some visual tests on a sketch drawn in order to see them with the same angular size (a sketch with bands having the same curvature ratio). You will touch the difficulty that is not intellectual but physical.
It is honestly possible to apraise this curvature near the pole, so difficult at the equator, conditions needs to be perfectly excellent.
We can also draw with curvatures because softwares give the general pattern of the planet as lot of observers does on Mars for instance for the general pattern in use, but, is it well the right method?
Stanislas-Jean


Post Extras: Print Post   Remind Me!   Notify Moderator  
Rick Woods
Postmaster
*****

Reged: 01/27/05

Loc: Inner Solar System
Re: Uranus cloud bands in a C8 new [Re: Cotts]
      #5496363 - 10/30/12 03:16 PM

Quote:

And here's a screen grab of the Keck IR shot which shows the amount of curvature that should be there assuming the bands/zones Stan is drawing are parallel to the equator of Uranus which they pretty much must be...

No resemblance.




I'm sorry, Dave; but I see a strong resemblance.

Edit: I notice there's no limb darkening in the Keck image, either.

Edited by Rick Woods (10/31/12 01:04 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
David Knisely
Postmaster
*****

Reged: 04/19/04

Loc: southeastern Nebraska
Re: Uranus cloud bands in a C8 new [Re: telescopemullet]
      #5496384 - 10/30/12 03:32 PM

Observing detail on Uranus is difficult in almost any telescope, especially with apertures smaller than 10 inches. That tiny disk and the powers needed to get it up to a decent size really strains the eye's ability to accurately detect any true detail which might be present without the eye/brain's own "noise" problems messing things up. Over the past 30+ years, I have viewed Uranus in 8 inch, 9.25 inch, 10 inch, 14 inch, 16 inch and 24 inch apertures under seeing conditions which should have allowed the detection of significant detail. Other than the limb darkening (which is quite easy to see even in modest apertures), I have never seen anything else on the disk with any of the previously mentioned telescopes. During recent observations which were triggered by some reports of alleged detail here in the planetary forum, in my 14 inch Newtonian at from 471x to nearly 600x, the disk appeared almost Q-ball smooth with a pleasant light bluish color. I will not dismiss the sudden temporary appearance of detail on that planet from time to time, but at least from my experience, I'm afraid that I am somewhat skeptical about routine visual detection of much band or spot-like detail on Uranus. Clear skies to you.

Post Extras: Print Post   Remind Me!   Notify Moderator  
stanislas-jean
Carpal Tunnel


Reged: 10/22/08

Re: Uranus cloud bands in a C8 new [Re: David Knisely]
      #5497235 - 10/31/12 02:27 AM

The main parameter is not the diameter but the contrast transfer ratio for capturing details of low contrasts (probably 1-2% level on the planet, not at the eyepiece).
A new time a 16" will not involve 2 times better the contrast level at the eyepiece with comparison of a 8".
Until your scopes at not characterised (PTV, RMS, etc... for getting a strehl not by a zygo report) this is useless.
Stanislas-Jean


Post Extras: Print Post   Remind Me!   Notify Moderator  
David Knisely
Postmaster
*****

Reged: 04/19/04

Loc: southeastern Nebraska
Re: Uranus cloud bands in a C8 new [Re: stanislas-jean]
      #5497396 - 10/31/12 08:00 AM

Quote:

The main parameter is not the diameter but the contrast transfer ratio for capturing details of low contrasts (probably 1-2% level on the planet, not at the eyepiece).
A new time a 16" will not involve 2 times better the contrast level at the eyepiece with comparison of a 8".
Until your scopes at not characterised (PTV, RMS, etc... for getting a strehl not by a zygo report) this is useless.
Stanislas-Jean




Sir, are you challenging my observations? The main parameter for determining the visibility of detail *is* the aperture used and only the optical quality may be second to that. Uranus is dim and small, so the more aperture one has, the better off one generally is. As for quality, I know precisely how good the optics are in my instruments (especially my 10 inch and 14 inch Newtonians, as I have actually had their figures measured). The 10 inch f/5.6 (custom figured by Enterprise Optics) has a p-v wavefront error of about 1/19.7 wave sodium light (4.1 nm RMS surface error or 1/67th wave RMS on the wavefront tested over seven zones) and a corresponding Strehl ratio of 0.991. In deference to Mike Lockwood, I have been asked by him not to disclose the precise figures for my 14 inch f/4.6 primary mirror that he refigured for me. However, suffice it to say that they are even better than the accuracy figures for my 10 inch Newtonian's mirrors. Mike refigured both the 14 inch primary and the 80mm (3.15 inch) secondary to a high degree of custom quality. I consider both mirrors in my 14 inch to be as good as can be obtained from *any* custom mirror maker, and they have proved their quality numerous times on the moon, the planets, and the deep-sky. My 10 inch f/5.6 Newtonian has a secondary obstruction of 21.4% of the aperture and my 14 inch f/4.6 Newtonian has an obstruction of 22.5%, so both obstructions are quite modest, especially when compared with some Cassegrain systems. The 16 inch I used to view Uranus with was at Lake Afton Observatory near Wichita, Kansas, and is a research grade Ritchey-Chretien used for research at Wichita State University as well as for viewing by the general public. The 24 inch Starmaster Newtonian I used to view Uranus at the Nebraska Star Party also had custom mirrors in it as well.

Any objection to a negative observation of detail on the disk of Uranus based on some alleged lack of optical quality figures presented is ridiculous. As I have clearly stated, from my observations (especially with this season's observations), I remain skeptical of claims of routine visual sightings of significant detail on the disk of Uranus. This is not "useless" but is a valid observation. Clear skies to you.


Post Extras: Print Post   Remind Me!   Notify Moderator  
stanislas-jean
Carpal Tunnel


Reged: 10/22/08

Re: Uranus cloud bands in a C8 new [Re: David Knisely]
      #5497421 - 10/31/12 08:35 AM

This means your 250mm of the described characteristics will be equivalent to 192mm clear perfect diameter. Then you can evaluate the scope transfer contrast ratio by FTM curves and the expected contrast level at the eyepiece which is in this case around the 1% level (for 2% on the planet itself).
This is the situation (the seeing level considered perfect).
Is it possible?
The numbers given may be discussed, especially the actual contrast feature on the planet.
Stanislas-Jean


Post Extras: Print Post   Remind Me!   Notify Moderator  
t.r.
Post Laureate
*****

Reged: 02/14/08

Loc: Upstate NY
Re: Uranus cloud bands in a C8 new [Re: stanislas-jean]
      #5497743 - 10/31/12 01:04 PM

I believe, that you believe, what you are seeing is detail on Uranus without question. But until Hubble or a ground based telescope shows detail at visual wavelengths similar to what you show, I think you are simply seeing "random albedo changes probably induced by seeing or your vision...and trying and really wanting to see bands on Uranus". This claim is no different than Lowell seeing canals on Mars...extraordinary claims require extraordinary evidence. It has not been provided to satisfy my critical thinking. If you truly are men of science, you must agree with this, your observation is merely a data point that doesn't stand up to logical scrutiny. And the catch is that there are soooooo few other data points with similar result. Like Fox Mulder (X-Files), "I want to believe", but unlike Fox, you haven't convinced me with the evidence presented. Can you not admit that the eye plays tricks with the mind? Truth is, as a visual amature astronomer, I'm rooting for you! But you haven't proved your case.

Post Extras: Print Post   Remind Me!   Notify Moderator  
telescopemullet
professor emeritus
****

Reged: 11/16/09

Re: Uranus cloud bands in a C8 new [Re: t.r.]
      #5497800 - 10/31/12 01:44 PM

Correct sir! I posted a similar argument (a couple of times in fact) back in the now locked thread that was largely ignored and ultimately frowned upon by those who were ignorant of the scientific paradigm. You hit the nail on the head.

Post Extras: Print Post   Remind Me!   Notify Moderator  
stanislas-jean
Carpal Tunnel


Reged: 10/22/08

Re: Uranus cloud bands in a C8 new [Re: telescopemullet]
      #5497854 - 10/31/12 02:28 PM

I think gentlemen you are reading with some imagination already fixed before having finishing the read, since the beginning.
You are not in agreement, but of what? We know this now.
Ho! but with which arguments, apart to expose this is impossible to see in IR.
Sorry but this is empty from your side, because you see nothing and this is your main objection, I think in general because this remains always too general and you cannot enter deeper. Please make some efforts.
Stanislas-Jean


Post Extras: Print Post   Remind Me!   Notify Moderator  
t.r.
Post Laureate
*****

Reged: 02/14/08

Loc: Upstate NY
Re: Uranus cloud bands in a C8 new [Re: stanislas-jean]
      #5497993 - 10/31/12 03:51 PM

Your retort to a logical argument, speaks for itself. The burden of proof and providing supporting evidence for your observations is on you...not those of us who have reams of data to the contrary of what you claim.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | (show all)


Extra information
2 registered and 7 anonymous users are browsing this forum.

Moderator:  Rich (RLTYS), star drop 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 16431

Jump to

CN Forums Home




Cloudy Nights Sponsor: Astronomics