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What to expect of Jupiter?

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#26 christheman200

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Posted 24 August 2013 - 03:50 AM

I'm picking up a glatter/TuBlug, and I will also need to solve my collimation locking problems before it arrives.
I didn't notice this before, but it now seems that my collimation locking screws aren't doing there job.
Cranking them all the way down, it still shifts when I move up and down, and this is a substantial shift.
I think I will need to install tougher springs to stop this issue, it should make the locking screws useless.

#27 corpusse

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Posted 24 August 2013 - 09:48 AM

I only image, so I'm not quite sure why I'm reading this thread, but I'd like to point out the seeing in Mississauga is usually terrible to fair. Last year I did not get one real good Jupiter image despite trying many times. I got one good Saturn this year (the low alt didn't help).

I'm not really sure why but real good seeing seems to be very rare here.

#28 dscarpa

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Posted 24 August 2013 - 02:15 PM

On Friday we at long last had clear skies at dawn and got my first look at Jupiter this season. Seeing was good and I was using a 5 XO and 7 XW barlowed to 175X-240X in my WO ZS-110. The two main belts and 3 others were sharp with a little detail and the polar hoods were easy to see. Europa, Ganymede and Callisto were the moons seen. In San Diego County seeing for lunar-planetary is often better on the coast than in the mountains or desert. David

#29 dscarpa

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Posted 24 August 2013 - 02:24 PM

On Friday we at long last had clear skies at dawn and got my first look at Jupiter this season. Seeing was good and I was using a 5 XO and 7 XW barlowed to 175X-240X in my WO ZS-110. The two main belts and 3 others were sharp with a little detail and the polar hoods were easy to see. Europa, Ganymede and Callisto were the moons seen. David

#30 Special Ed

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Posted 24 August 2013 - 05:20 PM

@ the OP,

There are already a lot of good pieces of advice about observing Jupiter in this thread so I'll try not to repeat them. An altitude of 35° is still pretty low and will definitely affect your ability to see detail in Jupiter's cloudtops, all other variables being equal.

The important thing is to keep trying. The good news is as the apparition progresses, Jupiter's altitude will increase. Now is the time to start training your eye to see detail. I was glad to read that you sketch--that's probably the best way to train your eye and sharpen your observing skills.

I suggest you sketch your observations even if you can't see any more detail than the 2 main belts. As time goes on, you will be surprised how much detail will reveal itself and your sketching skills will benefit from the practice as well.

Another suggestion--as far as magnification is concerned, the sweet spot for Jupiter is often 200x-260x. From your report, that is exactly the hole in your eyepiece collection. If your budget is tight, maybe you can borrow an ep from a friend in RASC that will yield that range in your scope. BTW, that 12" scope should provide you with some fine views of the King and the larger aperture makes color easier to see, in my experience.

Good luck with your Jupiter observations and please share your sketches here and/or in the Sketching Forum.

@ dscarpa--congratulations on your first look this apparition and thanks for the report. Jupiter is never the same from one apparition to the next--looking forward to my own first look.

Best regards to all. :)

#31 dscarpa

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Posted 25 August 2013 - 12:46 PM

I find that to be the sweet spot power wise for Jupiter as well. View at dawn. Last night my ZS was only pulling in 2 fuzzy belts when it wa low. Later on it was 5 belts and 3 moons but no spot. Next session my IM-715 or C9.25 is going to get a crack at it. David

#32 christheman200

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Posted 26 August 2013 - 02:55 AM

I only image, so I'm not quite sure why I'm reading this thread, but I'd like to point out the seeing in Mississauga is usually terrible to fair. Last year I did not get one real good Jupiter image despite trying many times. I got one good Saturn this year (the low alt didn't help).

I'm not really sure why but real good seeing seems to be very rare here.


Yeah, we normally have *BLEEP* weather here, but we've had a decent stretch for the past two weeks.
I haven't been able to make a sketch yet because of bad turbulence for the last while.

#33 christheman200

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Posted 26 August 2013 - 03:00 AM

@ the OP,

There are already a lot of good pieces of advice about observing Jupiter in this thread so I'll try not to repeat them. An altitude of 35° is still pretty low and will definitely affect your ability to see detail in Jupiter's cloudtops, all other variables being equal.

The important thing is to keep trying. The good news is as the apparition progresses, Jupiter's altitude will increase. Now is the time to start training your eye to see detail. I was glad to read that you sketch--that's probably the best way to train your eye and sharpen your observing skills.

I suggest you sketch your observations even if you can't see any more detail than the 2 main belts. As time goes on, you will be surprised how much detail will reveal itself and your sketching skills will benefit from the practice as well.

Another suggestion--as far as magnification is concerned, the sweet spot for Jupiter is often 200x-260x. From your report, that is exactly the hole in your eyepiece collection. If your budget is tight, maybe you can borrow an ep from a friend in RASC that will yield that range in your scope. BTW, that 12" scope should provide you with some fine views of the King and the larger aperture makes color easier to see, in my experience.

Good luck with your Jupiter observations and please share your sketches here and/or in the Sketching Forum.

@ dscarpa--congratulations on your first look this apparition and thanks for the report. Jupiter is never the same from one apparition to the next--looking forward to my own first look.

Best regards to all. :)


I will definitely try to sketch all of my Jupiter observing sessions in the future!
Of course, the seeing got worse progressively after that one good night, so no sketch yet.
I'm looking at getting a 6mm when it is possible. I fear I've already asked around for too many things in my local RASC (mount, barlow, diagonal, you name it!).
However, a friend, Jo, may have an eyepiece I could borrow for a while but I don't want to bother anyone until our next viewing session.

#34 TG

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Posted 26 August 2013 - 01:38 PM

However, when I push it to 340x with my ultima barlow it loses almost all of it's detail, and even the bands are hard to make out. This is odd because seeing was great, no wind no nothing. Jupiter was about 35 degrees up (a rough guess). Is this to be expected? Or is my barlow deteriorating the view? Could it also be other parts of the optical chain not being up to snuff?


Jupiter, unlike the other planets, doesn't take power well. I've noticed that that an exit pupil of about 1mm gives the most pleasing view, large enough yet containing a lot of details. Higher powers will make the lower contrast features on Jupiter, such as ovals and festoons, harder to make out. I'm not sure why this is the case. It may be that the image dimming at higher powers causes the eye to lose its ability to discern low contrast features.

The power for a 1mm exit pupil is easy to calculate: it's the same as your aperture in mm.

If you know how to star test, do it just when you are observing Jupiter. It'll quickly tell you if everything is ok with your optical train. The things to watch for are seeing, collimation and thermals. If all three are ok, then you can worry about other possible problems.

Tanveer.

#35 Scott in NC

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Posted 27 August 2013 - 08:08 PM

The power for a 1mm exit pupil is easy to calculate: it's the same as your aperture in mm.


And another easy to remember formula is that the focal length of the eyepiece needed to produce a 1mm exit pupil is the same length (in mm) as the f/ratio of your scope. E.g., an f/6 scope would need a 6mm eyepiece to give you an exit pupil of 1mm.

#36 dscarpa

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Posted 28 August 2013 - 09:56 AM

Sunday AM the mak showed about the same as the ZS. This AM I had the 9.25 with a 10 XW for 260X and there was quite bit more detail including the GRS! That side of Jupiter does have more to see. As to the spot it didn't jump out at you but it was easy. David

#37 dscarpa

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Posted 28 August 2013 - 09:58 AM

Sunday AM the mak showed about the same as the ZS. This AM I had the 9.25 with a 10 XW for 260X and there was quite bit more detail including the red spot! That side of Jupiter does have more to see. As to the spot it didn't jump out at you but it was easy. David

#38 dscarpa

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Posted 30 August 2013 - 02:15 PM

This AM I was viewing Jupiter with my IM715 using a 12 Delos for 250X with very good conditions. All four different colored moons were there with Io's shadow black and sharp but rather small. The GRS was coming over the limb and 5 belts with quite a bit of detail in them and the polar hoods was visable! What to expect of Jupiter? It would appear to be a lot given good conditions! David

#39 christheman200

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Posted 02 September 2013 - 09:15 PM

I have a post up in the reflector forum, but I might be able to get some help here too. It is now very obvious that my collimation locking screws are not doing anything or possibly making my collimation worse. No matter what I do the collimation drifts a LOT past 75 degrees up. Does anyone know of a possible fix? When I posted my thread originally, it was about shimming my mirror but it quickly turned into asking about my collimation locking problem. At first, I thought I had finally nailed the problem as a loose spider or secondary, but once that was dealt with it was clear that the mirror was drifting. I am using a collimation cap and once I get the dot centred at around 45 degrees, I tighten up the collimation locking screws. However, no matter how tight the locking screws get they do not stop the dot from drifting around 2-4 donut diameters across the surface of the mirror. Most drift is noticeable past 75 degrees upwards, with some noticeable past 25 degrees downwards. Any help is appreciated, thanks.






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