jupiter, grs, what should i be able to see?

[4lefts]

so i've spent some time looking at jupiter with my 8" dob, up until about midnight/1am-ish, so it hasn't been that high (but not that low either). i was wondering what i should expect to see with such a set up? with my eps, i can get up to 240x.

i can generally see the two main bands, plus a couple of other blobs. i think i could see the grs, but i'm not sure - is it really that hard to see? my girlfriend said she couldn't see it, which makes me think i'm seeing things? i didn't have my chair, which i find makes a big difference.

is there some way to check the position of the grs at a given time (a computer program maybe?). i see sketches and things that people make, and think, hmmm... i'm really not seeing that level of detail. do i just need to give it more time? would a filter of some kind help to bring out detail? wait till it's higher up?

thanks for any advice!

(i did bag m33, the triangulum galaxy, though it most certainly didn't look like a pinwheel...)

[Jove]

Hi,

Sky an Telescope have this page that will tell you GRS transit times. You may need to register for access.

I've never used as big an instrument as an 8" but in my experience details come out with time at the eyepiece, few things jump out at you. And yes, sometimes I think I imagining things. I think this is especially confusing when you have seen NASA images of something so you know what you think you should be seeing, sometimes it feels like my brain is adding in things that I can't actually see.

[FarSide]

Hello 4lefts, You should be able to see a decent amount of detail, actually. What you won't see, though, is what you expect from NASA images. I currently us (mostly though lack of gear) a 10mm eyepiece after grabbing it with both the guide scope, and a 20mm piece. I have a 5 inch refractor so my view may be different, but i see all four moons as pinpricks, and Jupiter with both north and southern equatorials.

Stupid question, but are you using the right piece , and are you focusing?

[4lefts]

thanks for the input guys! yeah, being raised on all those pioneer/voyager images doesn't help, which is why i'm trying to take my lead from sketches people make, and try to make out the kind of detail they do. there's a good column on this in this month's astronomy now.

focus is always tricky, with the atmospheric effects. i think my problems at the moment are two fold. first, its really[\b] bright. not as bright as the moon, sure, but pretty glaring, and that might make bright, low contrast detail hard to see. i was thinking about a baader neodymium (sp?) filter - anyone tried one? second, i'm just not giving it long enough - i have a tendency to put the scope out the back of my flat for a bit, have look at a few objects i know, maybe try a new messier or two, and then have a look at jupiter. i think i really need to spend more time on it, like jove says.

that said, i can clearly make out the four galilean moons, and the two bands you describe. and last night i think[\i] i could see a little lump on the top one of those (i.e. the "bottom" one really, as my scope turns things upside down).

i just checked the link jove posted, and the GRS should have crossed jupiter's meridian at 11:52 last night. i was looking about 1:00am, so i think this ties up with what i saw, assuming the GRS moves (i.e jupiter spins) from left to right in my scope... i don't know if i'm right making that assumption.

as for eps, i was using a 5mm (240x) which was sometimes ok, but other times didn't show any more than the 8mm, which gave 150x.

thanks for your help - if it's clear tonight i'll have another look (a longer one!) and report back.

[Moonshane]

for me anyway, the basic requirements for good planetary observing are as follows - all these really make a big difference:

ensure scope is cooled and accurately collimated

observe while seated

spend at least half an hour, if possible more, observing so your eyes adapt to the brightness and you have a chance of moments of good seeing

when you find the focus point, leave it alone; focus will come and go

every now and again look away within the field at a star, this allows your eyes to 'refocus'.

tracking mounts really help too, especially when magnification is high. I built an equatorial platform for my planetary dob.

use the appropriate magnification for the seeing. Jupiter often only allows around 120-150x and 240x would be unusual and usually soft and lacking detail.

with all the above your scope should reveal decent levels of detail.

good luck!

[Charon]

Not hi-jacking the thread but thanks for that great advice Shane, I must invest in a decent chair.

[John]

I spotted the Great Red Spot the night before last with my ED120 refractor and, as the night progressed, followed it's progress across the central meridian of the disk and across to the planets limb. It was very pale to my eyes - close to the tone of the brighter zones on the planet. I did not detect any red or pink in it at all. It nestles in a hollow in the South Equatorial Belt, a hollow which, to my eyes, seemed to have a slightly darker rim than the general belt tone.

All the above came and went as the seeing fluctuated as it usually does. The contrast of these features also improves as the planet rises higher and as your eye gets attuned to the brightness of the planet.

There were also dark knots in the North Equatorial Belt and a very pale rift in the SEB that followed the GRS around the disk. During moments of the best seeing I could see 6 belts in total plus a darkened north polar area.

[Moonshane]

I can see 'belt wars' erupting here - John has set a high bar at 6....anyone?

[Anweniel]

hey 4lefts, dunno if I can help much with this info but hopefully give you some comparison.

Caught my first view of Jupiter thursday night/friday morning at about 00.30, the skies were crystal clear for me and I have been itching to get Jupiter in the scope for weeks and getting up at silly o'clock for best position and been constantly dissappointed due to cloud cover. However I was biding my time thinking that I wouldn't get a good chance from my garden until about 1-2am, figuring it would pass my neighbours rooftop about then so had as it seems you do been hunting DSO's.

After a couple of stints checking out andromeda and dumbbell I suddenly noticed that there was a very bright and large object just below Aries and just peeking over my neighbours rooftop, in excitement at the prospect of it being Jupiter I lifted the scope over to a better postion and got my first ever view and I was absolutely over the moon (for want of a better phrase!)

At first I used my largest EP, a 32mm Plössl with a wide FOV and it was a clear orangey blob with 4 pin pricks on a 45° ish arc. So this confirmed I for I had finally nailed the target! so I tried a few more EP's to get a better view trying a 25mm 10mm 8mm, eventually found the 10mm to give me about best view. I was also using a 2x barlow without much trouble focusing.

So to give you an idea for comparison considering my lack of experience and equipment I saw a nice size Jupiter about 1/8 of the FOV in the EP and all 4 moons, could clearly see 2 blueish bands and some movement within the bands, the moons were appearing slighlty larger than your average star and clearly moons not stars by appearance. My equipment is a motorized alt az mount SW 130/650 2x barlow and 10mm EP so magnification was about 130x.

All in all I was very pleased with my view from the scope and it really did surpass my expectations ( especially when you see the pretty snaps others get on high quality equipment and vast experience + post processing). Your equipment and experience seems to be much better than mine and the massive aperture difference I believe should give you much better detail, already I have confirmed one thing from this experience and that I have read previously in these forums....magnification doesnt seem to be the key to getting the great view but a good aperture will give better detail and good seeing conditions.

Hope this is of any help, at least perhaps as a minimum standard to comapre too

PS sorry if this post is a bit waffly

[todd8137]

hi 4lefts,filters would help i never seen the great red spot till i did i use a couple on planets,a Neodymium filter,it does let me see the shapes in the bands the red spotscolors pop out as wellgreat on most planets ,color filters work as well orange ,yellow red,light blue, all work well on jupiter

avert your vision am sure you do thatany way most mistakes are made whenjust looking into the centre of a ep look around it with your eyes

what mag wasyou looking at the pinwheel with ?

cheers todd8137

[4lefts]

thanks folks. i'm glad someone has used a baader neo filter - that's the one i was looking at. it seems my experience is fairly typical, and that obviously jupiter will be better later in the year.

for m33, it was probably about 32x (38mm ep with a 1200mm fl, whatever that works out to). i just scootched down from m31 to have a look. honestly, you'd have to know it was there to not miss it. i should post a photo of where i was observing from, the streetlights are a joke.

[twotter]

I've seen the GRS through my 200P dob only once, and I checked it against Stellarium to make sure I wasn't imagining things

Otherwise the two main bands stand out well (apart from when the one disappeared), with occasional views of the lesser bands, though never as many as 6

[brantuk]

Astronomy Now magazine has a September schedule of GRS transits times on page 41 this month.

[John]

It's useful to be able to find the transit times of the GRS to confirm an observation but my advice is to make the observations 1st, jot down a few notes / sketches and THEN confirm where the features were.

On the number of bands and other detail visible, I always record the best moments of seeing when making reports. For much of the session I described above the planet presented the 2 main equatorial belts and a 3rd, more pale, to the south of the SEB. I could see indications of a feature within the SEB but it was only on those moments of really good seeing (and they really are just momentary on many nights) that the GRS, it's hollow in the SEB and the further cloud bands popped clearly into view.

This is why I strongly advise spending long periods of time observing the planets - it gives you more chance of being at the eyepiece and concentrating when the full potential of your scope is "unleashed" by a pocket of great seeing