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Jupiter Nov, 11-12

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#1 idp

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Posted 12 November 2012 - 02:12 PM

After Sandy and the snowstorm, there were a couple of decent nights in Connecticut so I could take a look at Jupiter with the 10" Clark refractor at Bethany.

Time of the sketch is 04.10ut, L1=237, L2=2, seeing III (improving during the observation). I only used ca. 230x as I focused on colors and intensities rather than fine details, so I went directly for a color drawing.

Please notice that the large projection in EZ following CM and the bay in NEB(N) were closer than they look in the sketch. Unfortunately, with colors it is difficult to make corrections.

Steady skies,

Ivano

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#2 Ed D

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Posted 12 November 2012 - 05:52 PM

I'm amazed at the color that can be seen with a 10" refractor. Nice sketch.

Ed D

#3 Chopin

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Posted 12 November 2012 - 06:19 PM

Terrific to cross reference the rift as seen from other member's sketches. You really have a ton of detail for A-III skies, Ivano. Bravo.

#4 idp

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Posted 12 November 2012 - 09:02 PM

Yeah, there may be a bit too much of yellow... It was a little bit hazy to be true but then the planet was very high in the sky, and I remember looking at it just before putting my crayons away and say "what the heck, that's yellow it's not my fault!"

Ivano

#5 Asbytec

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Posted 12 November 2012 - 09:59 PM

You know, George and Dean were commenting on a yellowish hue in the NTrZ. I had seen a bit of hue there, but took it to be more ruddy.

Indeed, on closer inspection, Jupiter's EQ zone does have a bit of yellow-buff hue, and the NTrZ has a touch of it, too. So see some yellow (but, maybe not that much) in Jupiter is not surprising, especially with some aperture.

So, Jupiter is kind of cream or flax yellow, and it's not your fault. :)

#6 azure1961p

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Posted 12 November 2012 - 10:16 PM

Ivano,

A lot of nice detail in the festoons and neb. It is interesting how haze can yellow jupiter... Ive seen it in different scope designs.

Pete

#7 idp

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Posted 12 November 2012 - 11:02 PM

You know, George and Dean were commenting on a yellowish hue in the NTrZ. I had seen a bit of hue there, but took it to be more ruddy.

Indeed, on closer inspection, Jupiter's EQ zone does have a bit of yellow-buff hue, and the NTrZ has a touch of it, too. So see some yellow (but, maybe not that much) in Jupiter is not surprising, especially with some aperture.

So, Jupiter is kind of cream or flax yellow, and it's not your fault. :)


There were whites indeed, e.g. the oval following the large protuberance right before the CM, or the bay on the other side of NEB, but the general hue of the zones looked distinctly yellowish to me. Maybe the haze or the instrument or both emphasized it, as Pete hints.

I think it's a good idea anyway to sketch what one sees, and decide later whether it belonged to the planet or not. It's also difficult to me to get "tuned" when I can only observe every now and then.

Ivano

p.s. I took a look at your very nice drawings, and was a bit surprised at how dull Jupiter looks to you color wise. I understand you observe with a 150mm, maybe those 10cm can make quite a bit of a difference. I remember that switching to 275x I could see many more details, but much less color.

#8 Asbytec

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Posted 12 November 2012 - 11:49 PM

If memory serves, there are some "white" features on the northern edge of the NEB. Maybe your "bay" feature is one of them. And along the edges of the EQ zone, too, much like you portrayed near the CM. The latter are very prominent near the GRS longitude giving the EQ zone a yellowish tint.

The "bay" is very difficult for me - in a 6". Impossible, probably. The white is hard to notice, for me, unless there is some off white to compare to and sufficient contrast. Needs some darker cloud's around it. :)

But, you know, there have been some observations where the NEB seemed to have a notch in it. You were observing ~ Sys 1 240. Hmmm...!! Might have seen that, too, without knowing it. No white, really, just a notch in the belt. I sketched one at CM330 near the preceding limb. (Doing the math to see if that one would have been closer to the following limb about that time. Brain just crashed...) Your preceding limb is to the left, right?

Point being, pretty sure a 10" refractor will show that "bay" as a white spot. But, to do that, the surrounding cloud tops probably need to be some off-white color...and they are.

Haze might play a role, sure, in giving the overall appearance as "yellow," but there are more yellowish hues to be seen, as well.

Yea, always sketch what you see.

#9 Special Ed

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Posted 13 November 2012 - 06:16 AM

Ivano,

Very nice sketch and observation. Your colors look pretty good to me if maybe a bit too much yellow (although the NTrZ has appeared distinctly yellowish to my eye lately).

I usually see the EZ as a dull white and rifts and bays in the two main belts as a bright (or brighter) white.

Festoons appear a gray blue or steely blue to me.

Good luck with your future observations (and weather). :)

#10 Jef De Wit

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Posted 13 November 2012 - 10:43 AM

so I went directly for a color drawing

Must be really tricky!

#11 idp

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Posted 13 November 2012 - 10:57 AM

OK, what about that? A bit less "yellowish", thanks to some GIMP magic.

Ivano

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#12 idp

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Posted 13 November 2012 - 11:06 AM

so I went directly for a color drawing

Must be really tricky!


It's not bad at all with Mars, but with Jupiter one feels you just don't have the time: not only placing and sketching details, but also doing that in the right color. No way I could do that in the classic 10 minutes - and the position of some details is not good indeed. Definitely need more training, or do strip sketches. Plus, you have to use a bright white light, because with the red you can forget telling what's the light blue crayon :lol:

Ivano

#13 Asbytec

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Posted 13 November 2012 - 11:29 AM

OK, what about that?

Ivano


You tell us? Is that more accurate?

Yes, sketching Jupiter takes some speed-sketching skills. Place the features best as possible across the disc, then focus on them in terms of color and finer detail. Sketch that detail in as it shows itself clearly.

Maybe try to sketch the preceding edge first, since those details will be gone in short order or fade into the limb darkening. You can always catch up with the trailing details as they cross the planet.

Jupiter take an hour sometimes, for me, to really observe, then re-observe (often several times) it's features. That just takes time, and probably more time in larger apertures.

It's like surfing, you cannot catch a wave paddling after it. You gotta stay in front of the power curve.

#14 idp

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Posted 13 November 2012 - 02:06 PM

OK, what about that?

Ivano


You tell us? Is that more accurate?


Good question. The answer may not be straightforward: the colors looked accurate that night (yeah, the think definitely looked yellow!), but then:

1. I was using a white headlight to sketch, turn it off to observe, turn it on again, etc. (Jupiter was a bit blinding itself, I could notice a huge difference between the eye I was using to observe and the other one). Could have it altered my perception of colors? Don't know.

2. Besides, that light was not the same as daylight so on the following morning mt sketches always look different to me :confused: This one was no exception.

3. Then, you scan the drawing and try to match it to the original (I only have LCD screens by the way, I heard they're not the best from this point of view).



Maybe try to sketch the preceding edge first, since those details will be gone in short order or fade into the limb darkening. You can always catch up with the trailing details as they cross the planet.


Good idea, need to try it. What I usually do is observe it for a while (like, half an hour but more would be better), then draw a band trying to make it straight (almost impossible :p) or at list at the right latitute; then, I identify on that band a clearly visible feature and place the others with reference to that one, rather than their actual position on the disk.

Thank you for the good conversation by the way.

Ivano

p.s. I also decided to first give the template a light yellow background, in order to set the general hue of the planet; all other colors are sketched over it. It usually works well for Mars and Saturn.

#15 niteskystargazer

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Posted 13 November 2012 - 04:50 PM

Ivano,

Very good sketch of Jupiter :).

CS,KLU,

:thanx:,

Tom

#16 Asbytec

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Posted 13 November 2012 - 11:17 PM

Ivano, some folks argue to use some ambient light to keep your eye tuned to Jupiter's brightness and the eye at photoptic(?) sensitivity. But, I find ambient light to be distracting as I observe with both eyes open (one covered.)

I do as you do, let Jupiter burn into my retina, then click on a flashlight (so you can actually see the paper) to sketch a detail. Turn it off, the readjust to Jupiter at the eyepiece. Maybe ambient light works, dunno, but I prefer to block ambient light and just focus on the subject.

Yea, it's amazing to look at a star and be 'blind' in one eye because Jupiter has killed dark adaption. :) Both eyes are open and relaxed, one is just covered looking at blackness in the palm of my hand or an eye patch. I think this helps both eyes relax, or maybe just allows me to relax. With both eyes open, you can kind of pretend you are using them both to observe Jupiter. That's a more natural condition.

Keeping ambient light might help color perception to some extent, until the cyclops eye is adapted to Jupiter. Anyway, yes, a flashlight does not produce sunlight where the eye is naturally adapted. So, who knows, really, what affect a flashlight has on color perception. Interesting point and maybe one of those fine, refined techniques for experts to use. Get a sun lamp. :lol:

Replicating color accurately is always difficult. With crayon it's a bit easier, less to choose from. :) With a billion color PC pallet, it can be a real bear to get it right. Then, matching the hues to every monitor on the planet is pretty tough, too.

But, yes, Jupiter does have some yellow on it so to portray it with yellow is correct. And some white. By the way, you captured 2 hues in the SEB, that's a feat sometimes, especially when you are discerning ruddy from brown.

Really, I did not notice the yellow in the SEB until the GRS rolled around and there were actually some "white" features along the SEB. Something to compare with the brilliance of the SEB hue helps to actually see the yellow as yellow instead of baseline for what might be white. And when those softer hues can be seen, really you have "resolved" more detail.

Anyway, thanks for indulging the discussion. Enjoying it.

"I identify on that band a clearly visible feature and place the others with reference to that one, rather than their actual position on the disk."

Yes, great technique. You almost have to do that. Sometimes I get lost, is that sketched festoon this one or that one? Arg! :)

#17 Asbytec

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Posted 14 November 2012 - 11:33 AM

Ivano, I can confirm Jupiter is indeed yellow, much like your second rendition. Under thin cloud cover and mag 3 transparency. It did indeed have a tawny hue. Confirmation and sketch will be posted tomorrow. :)

#18 frank5817

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Posted 14 November 2012 - 10:47 PM

Ivano,

Very fine sketching. I do think trying to capture some of the color visible is a great idea. I for one have much difficulty with color when viewing and sketching Jupiter and Saturn so I tend not to use it. I find Mars somewhat easier but still challenging. Details and color in your Jovian sketch work well.

Frank :)






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