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A frustrating but still rewarding Jupiter, Jan 5th

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#1 Eddgie



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Posted 06 January 2013 - 01:00 PM

It has been gray for the last week and a half with light mist on an off for the previous several days. The evening of the 5th looked like it was going to be good, so I set op in the late afternoon to allow for cooling.

Initially, Jupiter was only about 60 degrees above the horizon, and still in the thermal plume from my house rooftop. So much "Bad seeing" I think is local and not atmospheric. Tried as I might, I could not get a steady view. Seeing was maybe 3 arc Seconds, but wavering badly.

Jupiter was only showing major details, so I went in to watch Merlin.

90 minutes later, and Jupiter was now much closer to the meridian, and what a difference! Binoviwer in the C14 with 15mm Vixen NPL Plossls for about 260x. The seeing was steady enough that I had a very crisp view of the tiny disk of Io slipping into eclipse. I was not seeing any flaring off of the disk itself, but I was also not seeing a trace of albedo shading, and I think it was proximity to Jupiter.

On a whim, Iooked at the other Jupiter moons and even Ganymede was not showing more than a tiny hit of albedo. I did not simulate it to see if Osiris or Galilee Regio were in view though, so I don't know if it was still seeing or if there simply wasn't any higher contrast detail rotated into a good position to see.

The GRS was just about half of its length from the limb, so it was rotated far enough that seeing much detail was almost ipossible becaue of the oblique angle.

The eddy structure following it though never fails to impress me. The long, "V" of the eddy struchture in the belts streched from just after GRS to well past the meridian. This is a staggeringly prominent feature. In 40 years of viewing Jupiter, I can't say that I have seen such a dramatic and dynamic structure. Absolutely amazing.

Lots of festoons in the temperate band, and a very dark spot just approaching the meridian on the Northern belt, which is iteslf quite turbulent.

I detected no small ovals but my attention was focused on the turbulence in the major belts.

My view however seemed to be strangely dim. When I went to 300x in the Binoviewers, I just didn't feel that the image was bright enough. Seeing was so good that I was able to exploit the magnification from that perspective, but the image was dim. 13mm Hyperions.. I may have to try a pair of Plossls just to see. But also, I think my transparancy may have been low due to water vapor in the air. I did not really see any scatter around Jupiter using 24mm, 20mm 17mm, 15mm, or 13mm pairs, but at the same time, the view just seemed dim at 300x.

Then, I started to loose detail. It did not appear seeing related, and even dropping down to 20mm Astro-Tech Plossls (which work well for me in the binoviewers), I just felt like my faintest detail was dropping.

Dew. It was very damp out (and again, why I think I may have had some transparancy issue), and even though my dew heater was turned up full blast, it was still forming out to about half the apeture.

I feel cheated.. LOL. A night of almost perfect seeing (wavering first diffraction ring on a nearby red star at 300X, about as good as it gets in the C14), and lots of structure on Jupiter, and defeated by dew.

This still remains one of the best Jupiter apperations I can ever remember, but I felt like last night could have been the best best best for me had the transparancy been a bit better and the dew not set in.

#2 george golitzin

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Posted 06 January 2013 - 08:32 PM

Well shucks, I feel your pain! But you did get some great viewing in.

I'm also astounded by the detail in the SEB following the GRS, and in general find this to be one of the most inspiring apparitions of Jupiter I can remember--although last season's eruption of the SEB was wonderful too.

Have you tried a large dew shield in conjunction with your dew heater? Like maybe a long tube of ABS flocked with felt or the equivalent?


#3 Asbytec


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Posted 06 January 2013 - 08:34 PM

You need to cool your house, too. Set it out before sunset. :)

Ganymede has to be near the limb, I believe, to show some of its more prominent features.

This apparition has been, well, stellar. Jupiter has shown me more detail and color that previously. I think she likes me.

Festoons in the temperate band? Which one? Having followed Jupiter since late October, I am more focused on double stars. Speaking of that, did you observe BU 87, the red, tight double star that passed very close to Jupiter?

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