Jupiter detail ?

[Charlie_132]

What time does Jupier get high enough up into the sky to be able to see detail on it using a 130p scope ?

Ive only managed to see he detail once at about 5:30am just as it started to fade .... I would like to see the detail again, but is there a certain time when it will be best visible ? As if i look at it at 3am its just a ball of light ...

[Matt Scunthorpe]

As time goes on it will rise earlier so will be visible at more friendly times.

[umadog]

Download Stellarium. That'll tell you when Jupiter will be high at a reasonable time. At 3am is should have been reasonable, as it's 30 degrees up by then. Of course it will nicer when it hits 50 degrees, and that's not until almost 5 am. It's odd if at 3am you aren't seeing any detail. Either the seeing was really terrible or your scope wasn't collimated or both. A miss-collimated scope will produce blurry views. Hope that helps!

[pallas15]

I have a 130 scope and unless you have really good "seeing" you wont see lots of detail.switching to the 10mm or 25mm + barlow will show some banding but poor atmospherics and light pollution will be more pronounced the closer you "zoom".Have been tracking it this morning and with the rainy,hazy skies where I am it is very hard to get good focus.If you focus on the small moons then the main disc should be well focused, but it has been in and out of focus all the time whilst tracking due to the weather.Of course collimation can be a factor,Im hoping mine is ok as the main mirror has no dot.have zoomed right into an object to get the disc showing and the secondary veins look central so fingers crossed.

[umadog]

Pallas, light pollution won't affect planetary views. Only seeing will. Some nights when it's muggy and mildly hazy can be the best as at those times the skies are steady. So it's worth going out on such nights when they occur.

You report that you're struggling to find focus. This may be a symptom of bad collimation. You will need to center spot your mirror. Looking at the secondary vanes, as you describe, indicates the positioning of the secondary, which is not an axial alignment. Specifically, this is not a way of assessing primary tilt, which is the adjustment most critical for high powered viewing. To measure primary tilt you need either a Cheshire, a laser (ideally a barlowed laser), or an autocollimator. You can also assess primary tilt using the star test (which involves a lot less de-focus than that required to see the secondary vanes) but I don't think that helps you with secondary tilt.

[Qualia]

Ay, as Umadog says, good seeing conditions override problems with LP, and assuming collimation is spot on, you'll also find that on average, Jupiter doesn't really need much more than about 140x.

A 4" frac from a heavily polluted city in the middle of a buning summer can easily make out the north and south equatorial belts, great red spot, the equatorial band and the north and south polar regions. If you stick with him, gradually, after 15 minutes or so, Jupiter reveals subtle markings in the north and south temperate belts and larger markings in the north and south tropical zones. The entire image in the eyepiece is really no bigger than a pea.

Another thing of great help is to observe Jupiter as much as possible on your different sessions. The more time with Jupiter in your eyepiece, the more skilled you get at tweaking out subtler, fainter features. There are folk who argue that filters also help viewing detail. I haven't used them but general advice suggests that Wratten numbers 8#, 11#, 82a#, 80a# do the business.

[pallas15]

Pallas, light pollution won't affect planetary views. Only seeing will. Some nights when it's muggy and mildly hazy can be the best as at those times the skies are steady. So it's worth going out on such nights when they occur.

You report that you're struggling to find focus. This may be a symptom of bad collimation. You will need to center spot your mirror. Looking at the secondary vanes, as you describe, indicates the positioning of the secondary, which is not an axial alignment. Specifically, this is not a way of assessing primary tilt, which is the adjustment most critical for high powered viewing. To measure primary tilt you need either a Cheshire, a laser (ideally a barlowed laser), or an autocollimator. You can also assess primary tilt using the star test (which involves a lot less de-focus than that required to see the secondary vanes) but I don't think that helps you with secondary tilt.

Maybe the post was a little unclear.I personally dont suffer from bad focus.On this particular night after torrential rain and intermittant cloud cover (from my location) the view changing from focused to unfocused as Jupiter was tracked in the eyepiece or just viewed.This was obviously due to atmospherics at my location.I dont understand why LP wouldnt affect planetary viewing.I dont mean natural LP in the sky but man made things such as lights,streetlamps,head lights etc that hamper viewing.From my viewing location I have very bright street lamps within 10 feet of my viewing area which cause flare or reflection issues at certain heights or directions.I think the OP seemed unaware of the difference in "seeing" due to atmospherics or indeed how this problem would increase as magnifications rose.He was asking what was the best time to see detail and although time is a factor in how we see an object due to its position in the sky and or light levels,there are many factors to consider to get that really good view (from the UK).The OP said that it was "just a ball of light".Jupiter from my location is very bright but ive tracked it from one horizon till I lose visibility and have always seen banding ,(albeit very faint due to the limitations of a 130 scope),but sometimes barely,again due to atmospherics.Some times the planet "flares" with a huge band of light or multiple diagonal flares.Other times its Chrystal clear.I think if colimation were the issue this would be all the time on every viewed object (please correct me if this is wrong).This light "flare" effect only happens on maybe Vega,jupiter,venus,which are very bright and at times when you can see the "glare with the naked eye.The other factor could also be the supplied EPs which arent the best admittedly.Thanks UMADOG for the advice about the primary and secondary as without a center dot i have been concerned that my view isnt the best it could be, I have followed my scopes instructions and used the airy disc method of checking colimation and it seems ok...I dont think thats the most accurate method because of the lack of center dot....I would assume that since I have the similar or same optics as the OP and are viewing from the same lat as the OP, with the same or similar weather as the OP,then our viewing experience would be pretty close.It has only been with the recent inclement weather that most of these "seeing" issues have arose,so I felt that it was hasty to pin the issue on just poor scope set up as there are many factors to "bad seeing" than just colimation.Maybe im not putting enough credit on colimation for delivering good views,but I took from the OP that he could focus,just not at that particular time..UMADOG ,would poor colimation cause some views to be good and others to be poor??..is it THAT critical or would it always cause the same problem with anything you tried to view??dont want to hijack the thread but maybe I have the same issues as the OP,Would be nice for Star watcher to mark their primaries on their smaller scopes....(ps) any advice on center spotting a primary ...thanks...

[umadog]

Pallas,

Artificial sky-glow (what we usually mean by LP) doesn't affect planetary viewing because the planets are relatively bright so they can punch right through it. Local lights causing glare that his your eyes or enters the OTA is a different issue, of course. That will impair everything as it can be very distracting.

I agree there should be banding on Jupiter from horizon to horizon. I also agree it would be odd for only some views to be bad due to collimation. Without more info it's hard to be sure, but I'd imagine the following might be taking place: The OP reported no detail when the planet was lower in the sky and some detail higher up. A possible explanation is that poor collimation combined with bad seeing at lower elevations may conspire to eliminate all detail. At higher elevations, with seeing issues somewhat relieved, a little detail may be getting through. So it's quite conceivable it could be both collimation and seeing issues. A second explanation is that collimation was just worse on the night when no detail was visible. If collimation isn't actively being maintained then it can drift around from night to night.

It's also true that collimation is very important: it's been my experience that on difficult planets, such as Mars, collimation makes the difference between seeing a featureless blob and seeing surface detail (that's with a 10", though). I can see how with a smaller scope, a similar scenario could play itself out on Jupiter. A scope with misaligned optics produces a blurry view and this will occur for all objects. It's more noticeable at higher power and it's more noticeable on objects that are brighter and show a lot of detail. The resolution of your eye is worse for dimmer targets, so a little miss-collimation is less obvious on those unless you really know what to look for.

Just to be clear: when you're doing the AIry disk method are you looking at the diffraction rings or are you defocussing to the point at which the secondary vanes are visible? The star test should be done at high power. You should de-focus enough to see these patterns:

http://www.willbell.com/tm/IMAGES/StarTest2.jpg

But note that at the eyepiece they look a lot smaller than that. If you're seeing spider vanes you've gone way too far.

I think the best way of spotting the primary is with a Catseye template: http://www.catseyecollimation.com/template.html They're re-usable and if used carefully are very accurate (to within about 0.1 or 0.2 mm). Pretty cheap. You can also do it with a home-made tool (the paper cone method): http://flylib.com/books/en/3.311.1.51/1/ I tried that also but found it was less accurate.

[pallas15]

Pallas,

Artificial sky-glow (what we usually mean by LP) doesn't affect planetary viewing because the planets are relatively bright so they can punch right through it. Local lights causing glare that his your eyes or enters the OTA is a different issue, of course. That will impair everything as it can be very distracting.

I agree there should be banding on Jupiter from horizon to horizon. I also agree it would be odd for only some views to be bad due to collimation. Without more info it's hard to be sure, but I'd imagine the following might be taking place: The OP reported no detail when the planet was lower in the sky and some detail higher up. A possible explanation is that poor collimation combined with bad seeing at lower elevations may conspire to eliminate all detail. At higher elevations, with seeing issues somewhat relieved, a little detail may be getting through. So it's quite conceivable it could be both collimation and seeing issues. A second explanation is that collimation was just worse on the night when no detail was visible. If collimation isn't actively being maintained then it can drift around from night to night.

It's also true that collimation is very important: it's been my experience that on difficult planets, such as Mars, collimation makes the difference between seeing a featureless blob and seeing surface detail (that's with a 10", though). I can see how with a smaller scope, a similar scenario could play itself out on Jupiter. A scope with misaligned optics produces a blurry view and this will occur for all objects. It's more noticeable at higher power and it's more noticeable on objects that are brighter and show a lot of detail. The resolution of your eye is worse for dimmer targets, so a little miss-collimation is less obvious on those unless you really know what to look for.

Just to be clear: when you're doing the AIry disk method are you looking at the diffraction rings or are you defocussing to the point at which the secondary vanes are visible? The star test should be done at high power. You should de-focus enough to see these patterns:

http://www.willbell....S/StarTest2.jpg

But note that at the eyepiece they look a lot smaller than that. If you're seeing spider vanes you've gone way too far.

I think the best way of spotting the primary is with a Catseye template: http://www.catseyeco...m/template.html They're re-usable and if used carefully are very accurate (to within about 0.1 or 0.2 mm). Pretty cheap. You can also do it with a home-made tool (the paper cone method): http://flylib.com/bo...n/3.311.1.51/1/ I tried that also but found it was less accurate.

thanks for the info and links umadog.

[faulksy]

later the better realy 3.30 were i live just getting nice and high

[Charlie_132]

Thank you all for your help, I had a look at 05:30 and could see alot more detail then when i looked at it at 5am ... I found that a little strange, but i have noticed how much the moons have moved since last week .. Quite amazing

[LukeSkywatcher]

Thank you all for your help, I had a look at 05:30 and could see alot more detail then when i looked at it at 5am ... I found that a little strange, but i have noticed how much the moons have moved since last week .. Quite amazing

The higher up in the sky object become (closer to the zenith) the better the "seeing" beomes. Its nothing to do with light pollution but rather atmospheric conditions. The higher up an object is the less amount of rubbish in the earths atmosphere there is to get through. So objects will ALWAYS look best the closer to being directly overhead.