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Why can't i see it?

jimmyjamjoejoe

By jimmyjamjoejoe
in Observing - Planetary

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jimmyjamjoejoe

jimmyjamjoejoe

Posted
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Ok, this is about the GRS.

My first view through a scope ever, was with my local astro group, looking at jupiter through a 100mm apo. I doubt i appreciated the view, and it didn't seem much better than the view through my 90mm achro. People commented how awesomely detailed it was, seeing festoons, easily seeing the GRS etc, but all i could see was a disk with 2 pretty distinct bands.

I figured it was just down to experience and conditioning (i'm sure over the last few months my eyes have learned to dark adapt much quicker, and pick out more details in the dark).

Anyway, after a handful of sessions with the achro, i was still getting pretty much the same results from jupiter, just a disk with 2 easily discernible bands despite the GRS being in viewing position at the time.

I have always viewed standing up, and generally my sessions would be an hour or so moving from one target to another, spending 5mins on each. Last week i decided to spend some REAL time on jupiter, with a seat, in order to try and tease out some detail. It went relatively well.

I decided i was going to go for the best of the best that night, i'd take all the time needed to get the absolute most out of the scope. It was cooled from the get go, having been in my car all day. The night was nice and clear, and after setting up, and spending 10-15minutes working from my low power eyepiece up to a 6mm, i settled back and got comfortable.

I spent the next 5-10 minutes tweaking the focus. At such a short focal length, the focus was really hard to get perfect, since when focusing, the image would wobble, and by the time it stopped i had to wheel the slow-mo controls since jupiter had moved from the FOV.

So it was *focus. move scope. check focus* then rinse and repeat for 15minutes... ;)

Eventually, i got it right, and spent the next 40minutes or so leaning forward at the eyepiece, with my arm outstretched wheeling the slow-mo every 15 seconds or so, basically viewing for 7 seconds, bouncing for 7 seconds. It was a nightmare to be honest.

However inconvenient it all was though, i did get some good viewing out of it. After 20 minutes or so, jupiter started to change. I took a 30 second break to rest my eye, but the effect remained. There was definitely more detail there. It wasn't epic, or even specifically detail... I can't put my finger on what was different, there just seemed to be more "texture" in the image... Almost "hints" of details, faint swirls near the belts that i couldn't tell if they were really there... I went home happy.

I got out again tonight, and did much the same. This time, with the intention of finally seeing the GRS. set up and focusing routine was the same. I spent roughly 20minutes at the eyepiece, then came back inside quickly to double check stellarium, because i wasn't even seeing a hint of the GRS. Yup, should be on view, moons are in the same place, guess i'm just not seeing it yet.

So i go back outside and spend another 10 minutes at the eyepiece, the faint texture begins to creep in, and i easily notice the difference in shade between the 2 hemispheres. The 2 bands aren't consistently wide, i begin to see lumps and bumps in them, but still no GRS. I realize it kind of sits half in one of the bands, so might appear as a lump sticking out the side if you can't differentiate the 2 colours, but all the lumps and bumps were on the other band. The one where the GRS should have been was pretty much consistently wide, and very distinct to me.

At this point a thin layer of hazy cloud rolled in and ruined the session. I left frustrated. I just don't understand how i can get to the point of seeing such details, without even seeing so much as a hint of the GRS, despite knowing exactly where to look (especially with the extra storms trailing behind it at the moment...).

I've also tried with and without a fringe killer filter, and tried dropping the magnification to a 12.5mm ortho. Still no joy. ;)

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Chris H

Chris H

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With your 6mm ep you have x166 which is high enough and by studying the planet for longer periods of time your eye will begin to tease out some of the finer details but the Great red spot is not always all that red often it is the great pale red or pinkish spot which makes it stand out a lot less from the background colours of the planet. It is sometimes difficult to see with either my 98mm APO or my 10" Dob. Atmospherics will come into play too you will have probably noticed that as you stare at the planet the image will drift in and out of focus it's the moment of clarity you are waiting for which can often be short lived. Keep going and you will pick it out but it may take time.

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Crunchard

Crunchard

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Hi JJJJ,

I'm with you on this one, never seen the GRS, all I see is the same as you - disc with 2 main bands. I find Jupiter very bright and that may have something to do with it - next time the scope is out I'm trying a filter ... although my only filter is an Orion Ultrablock ;)

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Stu

Stu

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Hi JJJJ

I've posted elsewhere the fact that my eyes are different and it's really only my left eye which gives me the kind of detail which I want. I cannot see the GRS properly at all with my right eye. It may be that it is down to differences in eye sight and the ability of your eye to resolve the detail. It sounds like you are doing all the right things training your eye to see the detail. The longer you look, the more you will see. Get the focus right, and then leave it! The temptation is to tweak it all the time but generally once you have it right, it is best to just wait for the moments of good seeing when everything will snap into sharp focus and you will see the detail. There are some nights when the seeing is bad and you just won't get it regardless of how long you spend.

GRS is very pale at the moment, but is big, much bigger than the barges which are a regular feature on the northern belt. Have enough magnification but not too much otherwise you will lose contrast and sharpness. Finally, a 90mm achro is probably towards the limit of scopes where it is visible. I can get it with my 66mm apo at around x100 though so keep trying.

Hope that is of some help

Stu

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jimmyjamjoejoe

jimmyjamjoejoe

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Thanks for the advice guys, I'l keep at it. It could very well be my eye, i'l try old lefty and see how it goes.

I've been finding lately i really have to make an effort to get my eye to focus when at the eyepiece. It's strange, as soon as i'm near the EP my eye just relaxes, in the same way it does when you daydream and find yourself staring through something... Maybe time for an eye test.

It doesn't feel like atmospherics. After messing with the focus for so long i did get it pretty spot on, and while there was some "boiling" occasionally, i didn't really notice any shifting in and out of focus.

It's just frustrating that i haven't even seen a hint of it, not even a brief flash. ;)

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umadog

umadog

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Indeed, that is your problem! The Jupiter disk in Stellarium is just for show, it doesn't represent where the GRS should be. I don't know if this is accurate: MVAS - Jupiter Now because I've not really used it as an observing tool. Looks pretty, though!

The border around the GRS is probably more prominent than the GRS itself.

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jimmyjamjoejoe

jimmyjamjoejoe

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Seeing must be excellent tonight too, although it is windy. Between gusts when the scope sits still i'm seeing far more detail after just a few minutes than i did after a 30 minute session at the eyepiece on a still night a couple of weeks ago. I'd go so far as to say the last 10 minutes viewing have been my best ever!

Super chuffed. :)

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Stu

Stu

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That's really good. It does make a big difference. I've actually not had too many nights if really good seeing this year but it does look good out there tonight. No observing for me though :-(

Stu

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Stu

Stu

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Crunchard, with your scopes I'm sure you must be able to get it. Keep at it! If I can see it in a 66mm baby refractor I'm sure a 250mm will do it. Seeing seems pretty good at the moment.

Stu

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Mr Q

Mr Q

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Decades ago, I have seen the GRS easily in just a 4.5" newt under only good sky conditions. Back then, it was said that the color of the spot was weakening into a pinkish color from a more darker red of years before then. The last time I saw it it was not impressive several years ago. If you can find some old earth-bound photos of Jupiter, the spot looks a lot redder than even in the Hubble images.

Some people back then thought the spot would eventually fade into obscurity in the distant future. From the looks of things, it may be true. And that's so sad because the three most spectacular details are the moons, bands and GRS. Even recently, there appears to be another smaller spot next to the original but it too is hard to detect - almost blending into the background cloud color.

So don't complain - just seeing it at all these days is an acomplishment when observing it visually. Who knows wether it will still be detectable a hundred years from now. so enjoy what you can see now.

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John

John

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From what i've seen, stellariums timings are wrong...

You can make some adjustments to the settings in Stellarium which makes it reasonably accurate I believe.

I rely on the Sky & Telescope applet though.

On variations in the visibility of the GRS, last time around the whole South Equatorial Belt had faded so that it was almost invisible but now it's back pretty much as dark as the NEB. Jupiter is a pretty dynamic planet !.

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