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Old 26-03-2016, 06:16 PM
Nab (Darren)
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GRS seen for the first time

I might be becoming a refractor convert... after a fair number of attempts to see the GRS with my 200mm Newtonian I saw it last night around 11:31pm as it cleared the limb of Jupiter in my (still new) Vixen 81ED.
At 89x with a 7T6 it was a prominent knot in the SEB that became more pronounced and more russety in colour as it approached the meridian around midnight..

Maybe it was just good luck, but I am really appreciating the colour rendition and contrast of the Vixen in conditions where I would never drag out the Dob..

Cheers.
Darren.
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Old 26-03-2016, 10:15 PM
JoeBlow
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The GRS should be easy in a 200mm...

Either you have have been very unlucky with the GRS being on the other side of Jupiter every time your out with the dob or your collimation may be out? You might need to check your dob...

Even in bad seeing and scope not cooled, I can easily see the GRS in my 200mm Newt.
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Old 26-03-2016, 11:36 PM
Nab (Darren)
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Clouds, cooling, tube currents, big indoor outdoor temp differentials all have conspired against me. Last night I would not have even taken the dob out to cool with the light high clouds aroubd 9pm and looking like getting thicker. Ballarat is a challenging place to observe from

Darren.
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Old 27-03-2016, 08:12 PM
JoeBlow
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Yeah, dobs are definitely more finicky!

To help improve the performance of the dob it's a good idea to put it outside to cool 1 hour before you plan to observe. Seeing is usually worst after sunset and gradually gets better during the night. So try to observe the planets later at night, usually the best time is before sunrise.

By the sounds of it you pulled some really good details with a 81mm! When everything comes together, detail in the 200mm should blow you away! Patients is the key with big dobs.

Last edited by JoeBlow; 27-03-2016 at 10:50 PM.
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Old 27-03-2016, 09:14 PM
BeanerSA (Paul)
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I read in an article the other day that the GRS is currently more bright and vivid than it has been in a long time.
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Old 27-03-2016, 10:23 PM
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CAAD9 (Adam)
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Quote:
Originally Posted by BeanerSA View Post
I read in an article the other day that the GRS is currently more bright and vivid than it has been in a long time.
I thought that might be the case. Last year at opposition I saw the GRS for the first time in my 10" dob. It was tough, lots of use of the blue and green filters and self doubt.

This year, holy cow! So much contrast. I can even clearly see the white winds around it separating it from the SEB.

Awesome views.
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Old 28-03-2016, 10:51 PM
Tropo-Bob (Bob)
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Originally Posted by BeanerSA View Post
I read in an article the other day that the GRS is currently more bright and vivid than it has been in a long time.
Seems that way to me also, but it is nothing compared to when I first saw it.
When I obtained a 8" reflector in 1971 (delivered in person by Laurel Hall) , the red spot was a very deep, brick red. There as no need to 'look' for it as it would be easily visible. From what I have read since, this was an unusual, and relatively short-lived event. Pity!!!

I just finished a session now, observing the Spot with a 4" Vixen ED, and also viewing Io as it gradually reappeared from Jupiter's shadow.
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Old 28-03-2016, 11:50 PM
JoeBlow
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Check out the view of the GRS from Pioneer 10 taken in 1973 I believe. So much bigger and darker!
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Old 31-03-2016, 10:35 AM
Nab (Darren)
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30/3 update:

Cloud free and a GRS transit allowed me to compare my Newtonian and refractor side by side. Hopefully this is useful to others seeking to see the spot and maybe not succeeding.

The dob cooled for about 30 mins and collimation was checked and found satisfactory.
10:10pm Jupiter is just emerging from a distant obstruction - looking washed out @ 92x in the dob.
10:20 clear of the obstruction and the GRS should be seen on the limb. Not seen. Equatorial Bands are the only clear surface detail with graduated shades towards the poles. View more washed out at 171x. The dob appears not to be at thermal equilibrium as there are obvious ripples in both infra and extra focus images.
10:30 over to the refractor. GRS immediately seen @89x. Fainter and less intense colour than observed on the 25th. Banding not as distinct.
11:10 GRS is about 1/3 the way across the face. Dob is now less washed out, both the dob and the refractor showing obvious colour - a pale red. (Not russet as described on the 25th). Dob @171x fading in and out with seeing. Refractor @89x stable with stronger colour.
11:22 views in the dob noticeably improved. Either the dob is finally cool or sky conditions have improved markedly. Maybe both. GRS now very obvious (as I know what to look for) but seeing still a little patchy making the focus soften. Contrast still better in the refractor. The Tropical bands do not resolve themselves clearly in either scope.
Dropping to 96x in the dob the view is more stable, less washed out and the tropical bands more distinct, but not sharp.
11:30 GRS on meridian. @171x the dob holds the focus well with pale red colour. Banding still looks somewhat washed out.

When I packed up at ~11:45 the LMC SMC, 47Tuc M44 M41 and the coalsack were all clearly visual objects. The sky looked good - unfortunately I had to get to bed!

So, I can understand why I had not seen the spot to date. It's not as red or as obvious as you might expect in the in dob. It would be easy to miss unless it was right on the meridian and if you did not know how it should look in that scope.
Conditions were clearly not ideal early on in this session, but similar conditions are more the norm here than the exception.

Results do seem to suggest that the smaller refactor certainly wins on contrast, colour rendition and with a smaller aperture is less susceptible to atmospherics at least on such a bright object.

Cheers,
Darren.
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Old 01-04-2016, 07:54 PM
JoeBlow
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Great to hear your caught the GRS in the dob!

It sounds like you have fairly bad seeing in Ballarat... Under ideal conditions and scope fully cooled the dob should, at least theoretically, have a clear advantage over the small refractor.

Yesterday at 7:10pm I viewed Jupiter through my 8" F5. There was still day light and Jupiter appeared like a tiny yellow light in the sky. Even before achieving perfect focus the GRS was very obvious and showing colour. However the GRS was on the meridian making it easier to see. Jupiter was shimmering quite badly as I hadn't given the scope time to cool. A few hours later I was seeing much finer details, particularly in moments of excellent seeing.
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