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Peter Natscher
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Reged: 03/28/06

Loc: Central Coast California
Jupiter with GRS and Three Moons Putting On a Show
      #5597106 - 12/30/12 11:07 PM

I'm observing Jupiter tonight on 12/30/2012 8:00 PST from my home on the west coast of California with my new AP 175EDF. Jupiter is putting on a show with three bright moons close by and its pink GRS swinging around in view right now. Io will soon go into transit across Jupiter with its shadow following and trailing the GRS by 9pm. Callisto is passing in front of Jupiter closely south. Ganymede just emerged from behind Jupiter at 7:45PST and will disappear soon thereafter by passing into Jupiter's shadow at 8:30PST. What a show! I'm bino-viewing at 200X with two 18mm Tak LE's and a MarkV bino with 2.6X GlassPath.

Peter - in Monterey, California

Edited by Peter Natscher (12/30/12 11:50 PM)


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Asbytec
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Re: Jupiter with GRS and Three Moons Putting On a Show new [Re: Peter Natscher]
      #5597320 - 12/31/12 02:21 AM

So nice you broke away to post it. Yea, been there, too. Good for you.

Hey, while you're at it, I'd be curious to know if you can see something strange about Io (without cluing you into what that might be.) Here's a hint: its different than Europa, and not only in color. Pickering noticed it and a few of us noticed it recently, too. I bet you could.


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azure1961p
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Re: Jupiter with GRS and Three Moons Putting On a Show new [Re: Asbytec]
      #5597613 - 12/31/12 09:47 AM

Gotta do the A-B test with Europa. Hint: not merely magnitude difference: gotta take the whole view in of each. Preferably over200x.

Pete


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Asbytec
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Re: Jupiter with GRS and Three Moons Putting On a Show new [Re: azure1961p]
      #5597676 - 12/31/12 10:25 AM



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Peter Natscher
professor emeritus


Reged: 03/28/06

Loc: Central Coast California
Re: Jupiter with GRS and Three Moons Putting On a Show new [Re: Asbytec]
      #5597953 - 12/31/12 01:16 PM

I didn't notice anything unusual about Io's appearance other than it having a yellow-orange coloring and evenly bright disk -- no uneven albedo or surface details. Its brighter warm colors were a nice contrast to nearby darker blue-gray Callisto. The seeing was at best 3/5, not great but acceptable to get out to observe. All three moons including Ganymede showed sharp round disks without any diffraction surrounding them. The AP 175 did very well for this level of average seeing.

Quote:

So nice you broke away to post it. Yea, been there, too. Good for you.

Hey, while you're at it, I'd be curious to know if you can see something strange about Io (without cluing you into what that might be.) Here's a hint: its different than Europa, and not only in color. Pickering noticed it and a few of us noticed it recently, too. I bet you could.




Edited by Peter Natscher (12/31/12 01:18 PM)


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Dean Norris
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Re: Jupiter with GRS and Three Moons Putting On a Show new [Re: Peter Natscher]
      #5597973 - 12/31/12 01:28 PM

Peter,

The moons on Jupiter were busy last night with an occultation, an eclipse and a shadow transit. I observed it as well for a few hours last night with similar seeing conditions. The seeing will need to get better to pick up what Norme and Pete are talking about.

Congratulations on the new scope and Happy New Year. Dean


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Eddgie
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Re: Jupiter with GRS and Three Moons Putting On a Show new [Re: Asbytec]
      #5598054 - 12/31/12 02:05 PM

The clear aperture of the OPs scope and optical quality are such that he may not experience the diffraction effects to the same degree that an 8" or 6" obstructed scope would have.

His diffraction effects (MTF) would be about the same as my C14.

So, without giving it away to the OP, I would say that if he does not see it, I would not be surprised. He may have sufficient contrast transfer that it would simply not show, or be suppressed sufficiently so as to be far less obvious.


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Peter Natscher
professor emeritus


Reged: 03/28/06

Loc: Central Coast California
Re: Jupiter with GRS and Three Moons Putting On a Show new [Re: Eddgie]
      #5598686 - 12/31/12 08:13 PM

Well, I didn't see any of the newly discovered geysers shooting off from Io, if that's what you're asking. I would leave that to the Mauna Kea observatories to see.

Quote:

The clear aperture of the OPs scope and optical quality are such that he may not experience the diffraction effects to the same degree that an 8" or 6" obstructed scope would have.

His diffraction effects (MTF) would be about the same as my C14.

So, without giving it away to the OP, I would say that if he does not see it, I would not be surprised. He may have sufficient contrast transfer that it would simply not show, or be suppressed sufficiently so as to be far less obvious.




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Asbytec
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Re: Jupiter with GRS and Three Moons Putting On a Show new [Re: Peter Natscher]
      #5598756 - 12/31/12 09:12 PM

No, not that dramatic.

Just a confirmation of the illusion that stumped Pickering pretty bad and Bernard for a while.

Okay, gotta clue him in at the risk of implanting preconceived notions and risk biasing an observation. Pickering noticed Io appeared a bit elongated, not circular. His subsequent science was, well, not up to speed. But, Io did appear elongated to him and others. Interestingly, we amateurs can repeat that observation.

My coffee hasn't struck yet, but his scope's higher resolution might just see it. It can be done in a 6" and larger obstructed scope (and this is not a 'fractor war comment, so please...) With a high end scope of that aperture, I am sure it can be done and really more amateurs should attempt it in very good seeing. It makes Io that much more fascinating.

That's the point, to get others to try it and be amazed at observing something new...if it is a new thing to others.


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Peter Natscher
professor emeritus


Reged: 03/28/06

Loc: Central Coast California
Re: Jupiter with GRS and Three Moons Putting On a Show new [Re: Asbytec]
      #5598840 - 12/31/12 10:23 PM

That misconception was due to Io's brighter equatorial vs. darker polar regions making the moon appear oval. I was observing at ~200X with the 175EDF and with 3/5 seeing at best. Io appeared too small to me to notice anything like this. I'm thinking a better night of seeing (4/5) and 400X might work. Since you bring this up, I will focus more of my attention on any Io surface irregularities noticed with the 175 in future observations.

Actually, the most interesting observation of last night's Galilean moon expo was giant Ganymede slowly disappearing behind Jupiter's shadow in 38 minutes after appearing from behind Jupiter. I could discern Ganymede's illuminated shape change as it slipped into the shadow.

Quote:

No, not that dramatic.

Just a confirmation of the illusion that stumped Pickering pretty bad and Bernard for a while.

Okay, gotta clue him in at the risk of implanting preconceived notions and risk biasing an observation. Pickering noticed Io appeared a bit elongated, not circular. His subsequent science was, well, not up to speed. But, Io did appear elongated to him and others. Interestingly, we amateurs can repeat that observation.

My coffee hasn't struck yet, but his scope's higher resolution might just see it. It can be done in a 6" and larger obstructed scope (and this is not a 'fractor war comment, so please...) With a high end scope of that aperture, I am sure it can be done and really more amateurs should attempt it in very good seeing. It makes Io that much more fascinating.

That's the point, to get others to try it and be amazed at observing something new...if it is a new thing to others.




Edited by Peter Natscher (12/31/12 10:30 PM)


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Asbytec
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Re: Jupiter with GRS and Three Moons Putting On a Show new [Re: Peter Natscher]
      #5598849 - 12/31/12 10:30 PM

Yes, it is a misconception, Io is not elongated. It just looks that way. I just thought it was so cool to be able to see such a thing, to repeat the observation that stumped the old masters. And, it makes observing Jupiter's moons that much more exciting, IMO. Yes, great seeing is a big help. Good luck with it and Happy New Year.

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Peter Natscher
professor emeritus


Reged: 03/28/06

Loc: Central Coast California
Re: Jupiter with GRS and Three Moons Putting On a Show new [Re: Asbytec]
      #5598892 - 12/31/12 11:14 PM

Since Io rotates at the same rate as it revolves, we are seeing different parts of Io's surface as it rotates around Jupiter every 1.75 days. I'm wondering if the appearance of an elongated shape for Io only appears sometimes because different parts of Io's surface shadings and colors will be seen at its different positions around Jupiter. You might need to know at what Io position around Jupiter Pickering observed Io displaying this elongated shape.

Edited by Peter Natscher (12/31/12 11:18 PM)


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Asbytec
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Re: Jupiter with GRS and Three Moons Putting On a Show new [Re: Peter Natscher]
      #5598966 - 01/01/13 12:29 AM

Good question. Not sure if there if a specific orientation is required. Io does have a brighter equatorial region and darker poles. Such an "elongation effect" might be visible more generally along it's orbit.

And, yes, the effect is very small. Very tiny. It's best to have Europa nearby for some reference to what circular is. In fact, to my eyes, it was much harder than observing 72 Pegasi at 0.57" arc. It might be best seen as Io is contrasted against darker cloud features during transit. Images show this transit effect readily.


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azure1961p
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Re: Jupiter with GRS and Three Moons Putting On a Show new [Re: Asbytec]
      #5599685 - 01/01/13 02:04 PM

I'm kinda confident he CAN see it despite MTF. I'm not as versed in the ins and ours of MTF but two things are skewing the results it would seem : the. 14 image will be considerably brighter better illiminating all of the disc and the angular resolution is twice as great as the apo. It'd be interesting to hear of Mr. Natschers finds. I'm pulling for flattened poles!

Pete


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azure1961p
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Re: Jupiter with GRS and Three Moons Putting On a Show new [Re: azure1961p]
      #5599690 - 01/01/13 02:08 PM

Ok Pete, here's a pic thru a 14 I think too of the effect on this link attached. Naturally processing exaggerates the feature.

http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/5597276/page...

Pete


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Asbytec
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Re: Jupiter with GRS and Three Moons Putting On a Show new [Re: azure1961p]
      #5600198 - 01/01/13 07:34 PM

Pete, that animation shows it nicely. I am guessing that is a real image and not exhibiting a sort of processing artifact. That's how it looks: elongated. Much more difficult in smaller apertures, but elongated none the less. Its just so tiny that its often overlooked, surely. I am confident Peter has plenty of scope for the job.

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Peter Natscher
professor emeritus


Reged: 03/28/06

Loc: Central Coast California
Re: Jupiter with GRS and Three Moons Putting On a Show new [Re: Asbytec]
      #5600265 - 01/01/13 08:19 PM Attachment (10 downloads)

Attached is an image from Christopher Go taken on 12-13-2012 that shows what you have been talking about -- namely Io's elongated appearance even as it transits Jupiter. Its elongated look certainly shows from darker polar vs. brighter equatorial regions.

Quote:

Pete, that animation shows it nicely. I am guessing that is a real image and not exhibiting a sort of processing artifact. That's how it looks: elongated. Much more difficult in smaller apertures, but elongated none the less. Its just so tiny that its often overlooked, surely. I am confident Peter has plenty of scope for the job.




Edited by Peter Natscher (01/01/13 08:20 PM)


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azure1961p
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Re: Jupiter with GRS and Three Moons Putting On a Show new [Re: Peter Natscher]
      #5600476 - 01/01/13 10:36 PM

It's an interesting phenomenon and I've seen it with an 8, Norme with a 6 so we think you have a great shot at it MTF and all. It does do better in the 300x's if your sky allows it. It'd be interesting to see how diffraction and MTF does factor in here. My scope has a 16% central obstruction but its still there even if its tiny. It is a subtle enough feature that I hadn't noticed it in decades of viewing because its that sensitive an issue . Europa being similar size is a great comparison example.

Anyway, clouds cleared an Sirius is barely twinkling - in New England that's almost scarey. Hope the seeing holds!!!!!

An FYI: tonight around 1:30am eastern time, Europa and Io will pass roughly within 20" of each other so it'll be a great a-b comparison example.

Pete

Edited by azure1961p (01/01/13 11:07 PM)


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Asbytec
Guy in a furry hat
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Reged: 08/08/07

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Re: Jupiter with GRS and Three Moons Putting On a Show new [Re: azure1961p]
      #5600568 - 01/02/13 12:00 AM

Jason brought it up after noticing it in an 8", Eddgie (I think initiated the observation) by confirming it in his C14. Pickering urged amateurs to observe it in 5" scopes. Yes, the "effect" is much more pronounced against the cloud tops. Looks like a bright dash mark to me.

Question though, does that mean we've actually been "resolving" it's equatorial band as separated from it's poles? I think so. Gotta run, Eddgie is coming. (Kidding, Eddgie, we've hit on this before...its an interesting topic.)


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azure1961p
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Re: Jupiter with GRS and Three Moons Putting On a Show new [Re: Asbytec]
      #5600625 - 01/02/13 01:11 AM

The whole trouble with the question is what's resolved? The closer you split the hairs the more it starts to sound arbitrary and opinionated. Diffraction is a form of resolution even if it isn't cut with the certainty of full angular resolution . It's an interesting topic but I've come to the understanding or appreciation that resolution isn't a point or line drawn with black in one side and white on the other but something that has many levels (frequencies) that all arrive at a point at close but diffrrent measures. I'm not trying to be ambiguous but there's no on and off switch that makes the answer so clear.

It's too complicated to cut so cleanly, so Id feel my observation and yours "resolved" it but up to the point diffraction would allow. It's not whole or complete, but its still a toe in.

Lol, I'm kinda proud of my diffraction effects on this little orb.

Pete

Edited by azure1961p (01/02/13 01:12 AM)


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