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Old 15-03-2017, 10:41 PM
AussieBill (Bill)
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Jupiters moons sighted but no red spot or bands

Hello,

Am Chuffed - I just saw Jupiter and 4 tiny moons on my 76mm x 350mm Dobsonian ($50 from Aldi).

Was puzzled that even though I could see tiny specks of light for the moons I couldn't see the bands or the red spot on Jupiter, arent they much bigger than the moons ? Jupiter was a small white disc.

4mm and 20mm eyepieces and a 2x Barlow lens.

What am I likely to be doing wrong ?

Bill

Last edited by AussieBill; 15-03-2017 at 10:44 PM. Reason: added questiomark
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Old 16-03-2017, 07:09 AM
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The Mekon (John Briggs)
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You are doing nothing wrong.
The problems lie in your expectations of this small scope, that does not have the optical quality and contrast of even a cheap 60mm refractor.
Also perhaps your observing, you may not have been observing long, and learnt how to wait for those steady moments of seeing that will show delicate detail. The best this scope will ever see under ideal conditions are perhaps the two brightest bands, but I would not think the red spot ever.
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Old 16-03-2017, 07:53 AM
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sil (Steve)
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john is correct, expectation disappointment is pretty common. contrast is the problem, Jupiter is too bright and there is little contrast between the bands or the red spot and it'll take a while watching for your eye to adjust. a filter might help and/or if your scope end cap has a removeable center you can just remove that to reduce the light coming into the scope as a way of dimming jupiter. You will never see anything through an eyepiece that matches the great photos we see, especially colours, our eyes generally see in black and white , even still things like the orion nebula are spectacular to see for yourself at an eyepiece.
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Old 16-03-2017, 08:55 AM
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mental4astro (Alexander)
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I knew that my first scope experience would come in handy one day!

My first scope was a 50mm refractor. Smaller than your scope, Bill, but it is my experience with it that will help you. Don't be discouraged - this astro thing is a learning process!

First, seeing astronomical objects through a scope is totally different than using a scope during the day for terrestrial viewing. The background is black. Then most things are soft in glow. And then you have the occasional object that is bright, and it is REALLY bright compared to the background AND that you are viewing at night, so your eyes and brain are set for dim light viewing, so these bright objects are really low on their surface contrast.

You need to slow down at the scope. Things will not jump out. We need to give our eyes time to adjust and re-learn how to see in these conditions.

I did see the two main equatorial bands in my 50mm refractor on Jupiter. Of course the Galilean moons as well. Biggest problem was the quality of the eyepieces - rubbish actually with what I know now. But the bands were visible, and it takes time. Squinting is actually a good trick to have to help reduce the immediate glare of Jupiter. Believe it or not, even covering a little the top of the scope, so reducing the amount of light coming in, can help too. It is matter of trying a few different things that will help out immediately. Filters are useful, but not the only trick astronomers have up their sleeve.

The Great Red Spot (GRS) is very illusive. Firstly it is not as cherry red as it once was. Today it is more of a pale salmon pink, and getting paler. And of course if it is not turned towards us, you just won't see it!!! I didn't get to see the GRS in my 50mm refractor. I have my doubts a 76mm scope will too. Yes filters help, but even with filters, the GRS won't jump out.

Saturn is another ripper. Seeing cloud bands in a small scope though may be too much of an ask, especially a modest quality instrument with modest eyepieces. You might fluke a sighting of the Cassini Division in the rings, but this will be a real challenge with your scope. It's up to you to prove that it can be seen in a scope as yours My 50mm refractor wasn't able to.

Even with larger, "better" scopes, seeing detail on the planets is difficult. Atmospheric conditions are the biggest hurdle. If there is a lot of thermal activity in the atmosphere, then the image shimmers like a mirage, and it doesn't matter the quality of your scope, you won't see anything. Actually in really poor seeing conditions ("seeing" is the term used to describe atmospheric thermal turbulance), a smaller scope actually has the edge over a larger scope! And even with great seeing conditions, these planetary details are VERY subtle, and require real patience and a keen eye to make out. Rush and you WON'T see them. Be impatient and you won't see them. Take your time and let your eye do its thing, and you will be richly rewarded. I still remember the first time I saw the polar caps on Mars!!! And then clouds on Mars! I wasn't expecting to see them, but I wasn't rushing, only letting my eyes do their thing. When you least expect things is when they slap you in the face hardest

I'll tell you what, I still have my 50mm refractor, and I also have an adapter to be able to use my current and better quality eyepieces with it. When the clouds decide to bugger off, I'll have another shot at both Jupiter and Saturn, and see what comes of it. I did this with the Orion nebula a couple of years ago using a better eyepiece, and I was stunned at how much more detail I could see with this eyepiece, my older eyes and the worse light pollution compared with 25 years ago! I also have an 80mm refractor, and I'll give that one a fang at the same time. I'm now curious to know exactly what these beasties can do now with the experience I have gained (I say, big noting myself!! ).

Alex.
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Old 16-03-2017, 08:57 AM
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Tinderboxsky (Steve)
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Also, what time of night were you observing? The best opportunity for viewing comes when Jupiter is at it's highest point in the sky - called culmination. Then there is the least amount of atmosphere to disturb and distort your viewing. Culmination is at about 3.00am in the morning at the moment. In a few months time Jupiter will be high in the sky in mid evening allowing observing at a more "civilised hout".

Steve
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Old 16-03-2017, 09:00 AM
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Quote:
Originally Posted by Tinderboxsky View Post
Also, what time of night were you observing? The best opportunity for viewing comes when Jupiter is at it's highest point in the sky - called culmination. Then there is the least amount of atmosphere to disturb and distort your viewing. Culmination is at about 3.00am in the morning at the moment. In a few months time Jupiter will be high in the sky in mid evening allowing observing at a more "civilised hout".

Steve
Yep! This too,
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Old 16-03-2017, 01:44 PM
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LaughingBeagles (Peter)
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Some great reading and tips. Thanks for the posts gents.

P.S. A quick filter question - I have a couple of filters (and a moon one). Of the No 80A (Blue) and No24 (Red) filters, which would be better for looking at Jupiter given it's brightness?

Never mind, Professor Google helped. 80A it is.

Last edited by LaughingBeagles; 16-03-2017 at 01:57 PM.
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Old 16-03-2017, 02:40 PM
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mental4astro (Alexander)
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Bill,

I use the 80A filter for Jupiter. It helps bring out the GRS. It stands out a little more than otherwise by enhancing its redish colouration beside a more blue surrounds.

You might like to download a program like Stellarium (free download) or one of the various astro apps like Sky Safari as these will give info on when the GRS is visible. Also specs on shadow transits, etc.

Alex
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Old 16-03-2017, 03:45 PM
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mental4astro (Alexander)
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I just remembered that I have a 76mm reflector too! It's one of the nasty Celestron FirstScopes, but I'll be able to use it enough to get an idea of what a 76mm reflector can do. I'll assemble the trio of scopes, when the clouds clear...
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Old 16-03-2017, 04:07 PM
Wavytone
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Hi Bill,

Another aspect that all have missed is that Jupiter rotates - even if your telescope is able, the red spot isn't always facing earth and you may be looking at the wrong time !

The rotation period is less than 10 hours so on many nights it's possible to see it, a couple of hours either side of its meridian times https://www.projectpluto.com/jeve_grs.htm

As others have noted it is a real challenge to see it in a scope as small as yours though I'd say not impossible, once you can see the brighter bands.
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Old 16-03-2017, 05:39 PM
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The Mekon (John Briggs)
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Sorry Wavytone, But Alex did mention this if you read carefully -

Quote:
The Great Red Spot (GRS) is very illusive. Firstly it is not as cherry red as it once was. Today it is more of a pale salmon pink, and getting paler. And of course if it is not turned towards us, you just won't see it!!! I didn't get to see the GRS in my 50mm refractor. I have my doubts a 76mm scope will too. Yes filters help, but even with filters, the GRS won't jump out.
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Old 16-03-2017, 06:34 PM
AussieBill (Bill)
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Jupiter - will have another go

Wow !

Thanks for all the tips.

Yes am a total newb at this. Am using stellarium to plan sessions

Will have another go at Jupiter when it is overhead, and will check out red spot times. I was looking between 9 and 12 pm last night, not long after the planet rose on the eastern horizon. Wondered briefly about "tangential" view through atmosphere but being as I could see the moons I was pretty happy.

Will sit down and have a decent go and be patient and see if further details emerge.

I guess I was very lucky, because my first observations using this little telescope were of our moon, approx 1/2 moon, and I saw gobsmacking craters and what I thought was amazing detail - this fed my expectations for seeing a bit more detail on Jupiter.

Must admit it took me quite a few attempts to be able to line up the telescope and reliably find things in the 20mm lens, then changeover to the 4mm lens for a greater magnification.

The local astronomy club has an observation night once a month and am going to the next one to have a peep through their telescopes to see the difference between my cheap one and a decent one.

Thanks again for all the tips.

Bill
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Old 16-03-2017, 07:43 PM
PhilTas (Phil)
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Alex,

Your first post in this thread is terrific, and IMHO, deserves a place where it can be seen by all newcomers, esp those like Bill who has started with a small scope, (and myself, but that's quite a while ago now).

A lot can be seen with humble starter scopes. I think most of us probably started this way. But not too much is in print about how to go about obtaining the best from both the scope, and ourselves in learning how to see.

There are other intro's of course, but I think yours explains things clearly and elegantly.

Cheers Phil
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Old 17-03-2017, 12:11 PM
astro744
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All this talk about how large a telescope and magnification you need to see bands and the Great Red Spot on Jupiter got me thinking and I thought what better to use to test this than my Tele Vue 60 refractor. OK not quite a 76mm short Newtonian but it will do.

I was up a bit earlier than normal this morning and noticed the GRS on Jupiter was to transit at 5:47am. I need to be at work by 6:30am and since it was only about 5:25 I decided to go and have a look. It takes all of three minutes to go from taking my Tele Pod out, mounting the 'scope and having an eyepiece in it pointing at Jupiter. It takes only the time it takes to boil a jug and make myself a cuppa for both the eyepiece and telescope to cool down.

It was a bit windy this morning and there was a bit of cloud but it was clear all around Jupiter. The waning Moon was completely covered by cloud and I only realised it was up when I got into my car to go to work. During this time Jupiter was not covered by cloud once. In these conditions I wasnít expecting the seeing to be great and when I first setup and switched to the 6mm setting on the Tele Vue 6-3mm Nagler zoom I saw Jupiter a bit mushy a sight I was not accustomed to in my little refractor expecting it to be sharp almost instantly and I put this down to seeing and almost zero cool down time when I first looked this morning. Within only 2-3 minutes it had improved dramatically and I was able to up the power and at each stage of the zoom I noticed what I could and could not see. I was using a Tele Vue 60 deg. diagonal and seated low on an adjustable astronomy chair.

6mm setting is 60x
5mm setting is 72x
4mm setting is 90x
3mm setting is 120x

At 60x the NEB & SEB were easy and the GRS was a little 'pimple' to the right of the south equatorial dark band, (SEB). East was up and North was left. The north polar region was a grey colour with no distinct band. The best way to describe Jupiter's two main dark bands (NEB & SEB belts) is like a 'seam on a cricket ball'.

At 72x the NEB & SEB were easy and the GRS was a little larger 'pimple' to the right of the south dark band. The north polar region was a grey colour with no distinct band. The south polar region was brighter than the north and had a hint of a thin band.

At 90x the NEB & SEB were easy and the GRS was a little larger again starting to appear like a small oval to the right of the south dark band. The north polar region was a grey colour with no distinct band but a hint of variation in it. The south polar band was a little easier but still required moments of better seeing. The two equatorial bands started to give an ever so slightly uneven appearance.

At 120x the bands were easy and the GRS was a little larger again but not as contrasty as at 90x. The two equatorial bands were definitely uneven in appearance with what was possibly festoons just coming into view but not distinctly or at least the uneven edge of the belt and the north polar region had a hint of a very thin band but it was rare. The south polar region had a definite band there.

I then added a Tele Vue Planetary filter to the same eyepiece and the overall contrast increased significantly but the greatest thing about this filter is the colour it gives to the GRS. I call this the Red Spot filter as it gives a saturation boost to the colour of the Spot without making the whole planet red. It is a fantastic filter! (now discontinued unfortunately).

The boost in red with this filter is greater at larger apertures and when I first used this filter on a 6" f8 Newtonian on the GRS I just couldn't believe how red it made the spot without affecting the colour of the rest of the planet to the same extent. The colour boost on the TV-60 was not as great as on the 6" f8 Newtonian but was there nonetheless.

I then wanted to test how small an image I can get before the banding is not visible. I tried the 16mm T5 Nagler (22.5x)and there was a hint of darker appearance in the equatorial region but I just couldn't get a steady image that seemed to blur more frequently with seeing. It is a very small image at 22.5x even for Jupiter.

I then tried a 9mm T6 Nagler (40x) with and without the Planetary filter. In fact this time the GRS was slightly easier without filter but it was only there in moments of good seeing and was very tiny and if I had not known that it was there I may not have identified it at this power. The two equatorial bands were easy at this power and the north polar region was more grey and less bright than the south polar region.

I then tried a 7mm T6 Nagler (51x) with and without the Planetary filter. The GRS was small but just visible with and without filter but again it was only there in moments of good seeing and was very tiny and if I had not know that it was there I may not have identified it at this power. The two equatorial bands were easy at this power and the north polar region was more grey and less bright than the south polar region. The image was noticeably larger than at 40x. In fact each 10x power jump makes for a noticeable and significant image size jump. Especially between 40x, 51x, 60x, 72x.

I was running out of time this morning but wanted to quickly try two other eyepieces, 8mm Clave and 8mm Brandon (45x). I could not use the filter on either as the Clave was not threaded and the Brandon had its own proprietary thread and I did not have the adapter. Both gave a lovely contrasty image and comparable to the Naglers but I was not comparing eyepieces here merely seeing what I could see on Jupiter at a given magnification and at 45x the equatorial bands are easy as is the colour/brightness difference between the north and south polar regions. The GRS was a 'pimple' to the right of the SEB. In case you're wondering I preferred the view in the Clave over the Brandon at least this morning on Jupiter. The warmer tone of the Clave does wonders for Jupiter! The Nagler T6 views were just as nice though but since there is no 8mm T6 Nagler it is unfair to compare against a different eyepiece.

I know you cannot compare a Tele Vue 60 with quality eyepieces to a 76mm 'store' telescope and 'store' eyepieces but I felt it important to make it known that a small aperture instrument operating at low powers is sufficient to see bands and the GRS on Jupiter. With the GRS though make sure you know when it is next on the central meridian and then give it a go. If you donít have the Tele Vue Planetary filter, try a light blue 80A. It wont be red but the contrast boost on the spot could be is just enough to make it 'pop' out. (I have an 80A filter somewhere so I'll try it too next time with the TV-60).

Note though with a Newtonian it must be collimated or what you see will suffer and this could be significant if instrument is considerably misaligned.

Hope you enjoyed the rather lengthy report. Since getting the Tele Vue 60, I have found I use this telescope the most out of all I have especially for quick planetary viewing. The setup is almost instant and the views are exceptional. For extended planetary viewing I either use another telescope on a driven mount or piggyback the TV-60 and use it. It is just a little too light to use alone on my GM-8 although I haven't tried without any counterweight yet. Having a driven mount allows for greater detailed and concentrated study as you are not distracted by a moving image and constantly having to nudge the telescope.


Hope you enjoy your astronomical journey for many years to come!
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Old 17-03-2017, 06:09 PM
Wavytone
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Sorry Wavytone, But Alex did mention this if you read carefully -
Well the GRS is visible in my 70mm refractor (f/6.7 with 4mm eyepiece, about 120X) - not easily - so I'd say there's a better than even chance the OP can see it once he gets accustomed to the faint colours. My 70mm also resolves Uranus as a tiny disk. Finding it is another matter. And my eyes aren't as young as they used to be.

Don't underestimate too easily what can be seen with 3-inch scopes.

Last edited by Wavytone; 17-03-2017 at 08:52 PM.
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Old 18-03-2017, 08:29 AM
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mental4astro (Alexander)
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Astro744,

Brilliant report mate!

Thanks for taking the time to actually do this, The forecast for the this week in Sydney is terrible, and I have no idea when I'll be able to get any scope time, so it is fantastic that you should do this. It is excellent that you saw the details that you did, as it shows what a good small instrument is capable of doing with good eyepieces. Blooming good benchmark
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Old 18-03-2017, 10:19 AM
AussieBill (Bill)
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Thanks Astro,

Thats very helpful and will have another go tonight - too cloudy last night.

Bill

Astro Said : "I then tried a 7mm T6 Nagler (51x) with and without the Planetary filter. The GRS was small but just visible with and without filter but again it was only there in moments of good seeing and was very tiny and if I had not know that it was there I may not have identified it at this power. The two equatorial bands were easy at this power and the north polar region was more grey and less bright than the south polar region. The image was noticeably larger than at 40x. In fact each 10x power jump makes for a noticeable and significant image size jump. Especially between 40x, 51x, 60x, 72x."
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Old 18-03-2017, 10:57 AM
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Merlin66 (Ken)
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When I first looked at Jupiter many many years ago using the Charles Frank Beginners telescope - a 50mm diameter, 1 diopter (1000mm fl) single spectacle lens mounted in a cardboard tube (!!) and a basic 20mm(?) Ramsden eyepiece I was advised to use the "" light blue 80A"" filter as previously recommended.
It worked for me and allowed me to see the bands and "just" make out the GRS.
Ohhhhh those were the days!
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Old 18-03-2017, 02:22 PM
Wavytone
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Ah you've just made me go searching my parts bin for a +1 closeup lens - I have a 55mm one.

A nice weekend project for my son on a wet weekend.
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Old 18-03-2017, 04:30 PM
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Agree. It is all about the three "P's" - practice, patience and persistence"

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..... Don't underestimate too easily what can be seen with 3-inch scopes.
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