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Jupiter 2013 02 08

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#1 chrisrnuttall

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Posted 09 February 2013 - 04:05 PM

Hello

Well, I finally got my EQ platform built and I at last I can observe at high power with my new 12" Orion Optics Dobsonian.
I made the platform myself because I didn't want to pay £400 for a watch house one, this cost me under half that to make and I am pretty pleased with it. I will post an image or other info if anyone is interested, perhaps even in the right forum!

Anyway Jupiter was lovely at 333x in the Orion. It has 1/10 wave optics and I used a Baader maxbright binoviewer with a 2.6x Baader corrector and a pair of 12.5 Baader genuine othroscopics.
The seeing was average but with several good moments in which I was able to glimpse faint and subtle detail on Jupiter. I'm afraid that the sketch makes it all look more colourful, bold and contrasty than it really was, I do struggle to get everything in my Jupiter sketches, getting the colours right and keeping them delicate and subtle at the same time.
There is a very bright pink oval in the SEB, and the belt itself is divided into two halves as the GRS approaches.
Interestingly for all the subtle detail I could see, oval BA was almost invisible, its effect on the STrB was easier in fact.
Also invisible were the series of white ovals in the north tropical region.
Another feature of note was the white rift in the NEB and a white oval in the NTrZ with accompanying dark ovals and barges in the belts to either side.
The NTrZ itself looked decidedly yellow to me.
The barges in the EZ seemed to be getting whisked away by faster current towards the centre of the zone, and there was a large bright oval area on the setting limb.

Hope you enjoy.

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#2 frank5817

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Posted 09 February 2013 - 11:28 PM

Chris,

Always a great pleasure to see your Jupiter sketches.
The equatorial platform will make sketching even more enjoyable as you get it exactly how you want it.

Frank :)

#3 Special Ed

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Posted 10 February 2013 - 12:11 PM

Chris,

Excellent sketch of the King. My observation is almost the same CM--interesting to compare the two.

Glad you got to use your tracking set up. You put it to good use. :)

#4 JeanB

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Posted 10 February 2013 - 12:45 PM

Wow, very detailed and beautiful sketch, Chris!

Jean

#5 chrisrnuttall

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Posted 10 February 2013 - 01:43 PM

I just viewed them side by side Michael, they are almost identical!
It's nice to see someone else's sketch of the same view, it sort of takes me back and makes me think things like 'maybe that barge was a bit fainter than I drew'. It's pretty cool to compare as we basically got the same details in the same places.

#6 Special Ed

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Posted 10 February 2013 - 03:43 PM

Chris,

Yes, I think they compare very favorably. Always great to have one's visual observation validated and a nice benefit of belonging to the far flung community of the Sketching Forum. :)

#7 chrisrnuttall

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Posted 10 February 2013 - 04:19 PM

Far flung is right. I think it very cool that we can get, say, seven comments in a thread and they are from; USA, Belgium, Philippines, Germany, UK, Australia and Canada....Who would we talk to otherwise? Ourselves probably!

#8 azure1961p

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Posted 10 February 2013 - 04:59 PM

Wow I love that sulphur yell in the NTB. How big do you do your sketches by the way - diameter?

Glad your platform is a success. The one I've got is 90 per ent done - I just need to have a couple 3/8" steel rods machined to drive the platform on its arc. I glassed it and all so its stiff.

Nice to hear of your success. What's your run time on it?

Pete

#9 Ed D

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Posted 11 February 2013 - 09:27 AM

Superb sketch, lots of detail.

Ed D

#10 Chopin

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Posted 11 February 2013 - 09:53 AM

Chris, I simply cannot refrain from staring at your sketch. The color renditions, the soft and realistic shading...so beautiful. Such miserable weather here in the northeastern US that I haven't pulled out the scope in weeks. Your sketch reminds me of what I love most in observing.

Best of all, I'm pleased to hear of your equatorial platform. I am a novice ATMer at heart, so I can appreciate your desires to tackle such a project. Good for you, and I can't wait to see an image of the setup.

#11 niteskystargazer

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Posted 11 February 2013 - 12:13 PM

Chris,

Verg good sketch of Jupiter :).

CS,KLU,

:thanx:,

Tom

#12 chrisrnuttall

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Posted 11 February 2013 - 04:32 PM

thanks all, the yellow is has ended up a bit too strong really, but it was there!.

The weather has been rubbish here too, we are getting wild swings between huge low pressure systems full of rain and snow from the USA, and biting cold northerlies from the arctic. Hardly any clear skies at all, and if it is clear there has often been strong winds.

I designed the mount to track for an hour and a bit, I got an hour out of it on Friday night with an inch or two left at either end, that's good enough for me.
It's made from laser cut 3mm stainless steel which I TIG welded together, but it is a little bit flexible and vibrations take seven or eight seconds to die away now, as opposed to two or three seconds for the Dob sitting on grass. I think I have worked out that it is the angled plate that the north sector rollers are fixed to which is a bit springy, so I am going to take it to work tomorrow and weld a strip of L section along it.
I have really enjoyed designing and making it, I just manage projects and tell other people how to make things at work now, so actually making something again has been good.
One thing I am quite proud of is that it is the type with a polar axis shaft, and I drilled it out to take a laser pointer, so polar alignment is a doddle!

#13 Chopin

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Posted 11 February 2013 - 07:22 PM

The mount sounds very nicely designed. One hour of tracking is impressive.

#14 azure1961p

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Posted 12 February 2013 - 12:10 AM

If I can get fourty minutes ill be very happy..


Bravo Chris

Pete

#15 chrisrnuttall

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Posted 12 February 2013 - 05:13 PM

Pete

how is your mount made?
glass (fibre I presume) sounds interesting, I never event thought of that, but it would definitely help with the stiffness. Is it made of wood underneath?

Do you have someone to machine your shafts?
I'll do them if you get stuck, but I think postage might be a bit tricky!

#16 idp

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Posted 13 February 2013 - 03:33 PM

thanks all, the yellow is has ended up a bit too strong really, but it was there!


I understand what you mean. I happened to be drawing at the eyepiece, notice that yellow that looked a bit unnatural, get back to the eyepiece and say: "What the heck, that thing is yellow not my fault!".

Awesome drawing by the way.

Ivano

#17 JimPie

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Posted 14 February 2013 - 01:56 PM

Chris,
I like this a lot. Great detail and excellent observing/sketching. Yes the yellow is there, don't fight it. ;)

#18 azure1961p

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Posted 14 February 2013 - 06:46 PM

Hi Chris,

It's birch plywood with parts sheathed in 6ounce fiberglass cloth saturated in epoxy. A lot of folks in developing their platform had complained and reworked the platform the telescope actually sits on as flexure is an issue. Even with the glass cloth it still might be, but I have heavy aluminum angles if need be. I have two ac synchronous motors which in turn need the 3/8 SS rods machined to fit. As of yet I have no regulating electronics to speed up or slow down the drive rate so after the rods, that'll be my next objective.

I'm truly truly looking forward to having the eight inch tracking - it's a high power scope that's long over due for tracking. The Ranger too but it doesn't too out at 500x like the reflector.

I also have my thermal devils at bay. Do u have active cooling Chris?

Pete

#19 maroubra_boy

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Posted 15 February 2013 - 08:09 AM

Fantastic sketch, Chris. Really fantastic.

Alex.

#20 chrisrnuttall

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Posted 15 February 2013 - 04:16 PM

Pete

I have made a rear cap out of laser cut polyethylene foam which is a snug push fit onto the rear of the tube, in that I have mounted three 90mm axial fans which I use a PWM speed controller to run. The air hits the back of the primary mirror and because the cap seals the back of the tube it is forced to rush around the sides of the mirror and up the tube. I know this does not surgically peel the boundary later away but it seems to do really quite well, the way I see it is that the fast air rushing past the mirror will create low pressure and drag the boundary layer off from the centre to the edges.
If I run the fans at full speed while observing I can actually see the turbulence it creates in the image, but using the speed controller I can tune the speed to the thermal conditions of the night in question.
In the early days I did quite a bit of experimentation turning the fans on and off to observe the difference. Some nights is was obvious, other night not so obvious, but over the years I am very happy with it. I have read your reports of side swiping the boundary layer and I thought I would do it if my way didn't work well, but I don't want to make a big old hole in the tube if I can help it.

I also made a nichrome wire secondary mirror heater pad to stop it dewing up. I live a mile from a river in an area that should be marshy but has had drainage ditches put in over hundreds of years by people working the land, it can get pretty damp at night!

I really do enjoy making my own accessories to the
specification I need!

I'm going to see if the clouds have parted enough to let me see 2012 D14, there was a tantalising strip of clear sky in nearly the right place at 8:30, but it closed before I could star hop to the right area.

#21 chrisrnuttall

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Posted 15 February 2013 - 04:18 PM

Nope, it's getting thicker. I suppose that's where the forum got its name!

#22 azure1961p

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Posted 15 February 2013 - 08:09 PM

I did some muddling around with an eyepiece dew heater around Thanksgiving. I'm going to make one for my 50mm finder too as its imperative for deepsky star hopping to see the star fields clearly.

The boundary fan thing I truly enjoy but its probably half as apparent for me as the rear fan in terms of flare reduction in stars and things. It's real but its more subtle. Below 200x I would say its negligible in my 8".

One thing that was apparent from that thread on thermals is truss designs have a different dynamic than tubes . Apparently negative airflow is beneficial for trusses.

The making of a hole in the tube is a thing that most folks are apprehensive about - indeed its taken me since 1994 to do it to my reflector lol !!
I love it though.

Pete

#23 azure1961p

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Posted 16 February 2013 - 10:17 AM

The cap really helps . Without it the thing still seems to work for me but there's no denying the sealing off of one end makes for a far better efficient system. If ever you do decide to put a side fan in buzz me and I might be able to save a little rework - namely proper positioning of the fan to mirror.

I didn't realize your scope was mod'd out like it is - nice job. I looked for Nichrome wire but ended up with resistors soldered to copper braiding- flexible and hot! I find with a blowing fan the secondary is fine but the finder objective and ocular dew up.

Pete

#24 PeterDob

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Posted 16 February 2013 - 12:38 PM

OMG... What a beautiful sight!!! :jawdrop: Chris, you did a wonderful job with this sketch. My sincere compliments...

Peter






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