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Dome Observatory and Wind protection?


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Posted (edited)

A general chat has been taking place about future retirement plans, not for a while yet, but best plan ahead.

I will likely move and down size, enabling me to have an observatory, if the new location allows (note it most certainly will!).
So my ponder is does a dome give good wind protection?
I presently observe on a part open pad, it has fences on two sides, but the wind jiggles my scopes if strong enough.

So the above ponder has been verbalised and  now here on SGL, what do you fine folks know about this please?
 

I was unsure where on earth to post this question and some kind Mod has moved this to DIY Observatories, Thank You. 👍

Edited by Alan White
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I had an old fibre glass dome a few years ago when it was open and windy it  blew the sliding hatch clean off I had to repair it with a aluminium brace never blew off again but really banged in high winds no doubt there better built now.. As for mount wobble the new fiction mounts are meant to unaffected by strong wind good excuse to buy a new mount.

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Interesting to hear about your plans Alan, sounds like some nice opportunities for better observing and potentially darker skies ahead. I’ve never owned an observatory so can’t really give any in depth experience, but I did use a dome observatory for few years in my late teens and early twenties - it belonged to my local club, was made of wood and brick, and housed a 8.75” reflector. I remember the excitement of observing Saturn, Jupiter and many DSOs, and I have a real soft spot for dome observatories as a result. What I do recall is that it allowed for the possibility of observing in comfort, regardless of how windy, or frosty or cold it was. I suspect the dome had to be rotated away from the wind, restricting which objects could be seen, but can’t remember or sure.  It was a faff to get it ready, but a joy to observe in. But it was a long time ago and I have probably forgotten all the downsides. 

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Whilst not perfect, a dome will give significantly more wind (and local light) protection than, for instance a ROR.

However that's only one factor. Thinking about an observatory to last into later years, some other things I'd consider include:

  • Physical accessibility. Most (all?) of the amateur domes I've seen have low height doors. You have to bend over/duck down to enter - is your back going to be happy with that or would it be a bad start to the night?
  • Your future physical strength. With a ROR you don't need to have powered retraction but you might want to consider gearing the mechanism to reduce the effort. it's probably desirable and it's quite easy to fit a motor. With a dome personally I'd say it's essential. Turning a dome by hand must be a right faff, backwards and forwards between the mount and the dome as well as the effort.
  • I know you're a (almost exclusively?) visual observer, are you going to be happy with the more enclosed sky view that a dome will give as opposed to a wide open vista? Especially if you're in a nice location.
  • I think at the moment you're using an AltAz without goto. Staying with that style of mount/observing would make syncing a dome tricky, though not impossible.
  • Comfort. As you'll be less exposed to both wind and sky in a dome you will be warmer.
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8 hours ago, LuckieEddie said:

I know you're a (almost exclusively?) visual observer, are you going to be happy with the more enclosed sky view that a dome will give as opposed to a wide open vista? Especially if you're in a nice location

Ed, thank you for your comments and your correct in many of the assumptions. 
I am mindful of the above point more than any other, but not sure what two more walls will add to my existing set up.
Add a roof and its instant (nearly) observing of course.

 

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When I had a dome I considered a faff, should of got a ROR if I had the space for one but didnt and a dome was a more suitable temporary soution at the rented house, I sold it in the end to a member here, I cant recall who now, and hope he had many happy nights.

Edited by Earl
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My experience is that a dome will give very good wind protection. It also keeps down stray light.

No experience, yet, with a ROR but intend to find out within the next year.

 

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Hi Al,

As you know, I have had a Pulsar dome for 20 months and would not change it for anything.  During that time I have had my two refractors permanently set up in perfect balance etc etc, etc.

It has allowed me to enjoy long sessions and very short sessions because there is no set up/break down time involved and the scopes are at ambient.  It has allowed me to observe in the sort of windy conditions that I would otherwise spurn, in complete comfort but  I would never use it in strong windy conditions.  It is a fair point about losing the open sky with a dome . This troubled me and still does, but  is why I have the 12" Dob so that I can enjoy both on any session. 

I would heartily recommend  a dome, and you know where I am so you must pop over and see how you feel about using one. 

Steve

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28 minutes ago, Saganite said:

I would heartily recommend  a dome, and you know where I am so you must pop over and see how you feel about using one.

I am also in Cambs at the moment.  Please DM me your address and I'll likely drop by when convenient for you. I'd send you my address but don't actually do any observing in the UK. That said, if you fancy coming over for a pie and a pint ...

Paul

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Never regretted getting a dome. Had it 20 years. Not only does it give good wind protection, but most of the time when observing, the covered bit is above your head so the heat loss from your head is reduced. More comfortable all round. It also helps stray light entry 

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+1 for a Pulsar Dome. I can image in a stiff breeze if the aperture is on the leeward side, and it does shield a lot of stray light if you are in an urban location. I can’t comment on the heat retention aspects as I use it remotely, but it has to be better having a roof over your head. 
The one big advantage the roll off roof has is you don’t have to worry about keeping the aperture aligned, but I’ll live with that.

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30 minutes ago, Stephenstargazer said:

Following with interest as considering simìlar possiblity after house move 🫰. Do the 'pro domers'  have a minimum size to recommend ?

Yes.  Domes are never too big, only ever too small.  I have had a self build 9metre aluminium dome for 24 years and we're still short of room!     🙂 

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Depends on size of scope and if you intend to have visitors regularly.

My 2.1m Pulsar has been ideal for my Tak 4inch or C11. 
 

The most important consideration is slit width. Especially when the scope is looking thru it tangentially. The newer Pulsar 2.2m has a wider slit

1 hour ago, Stephenstargazer said:

Following with interest as considering simìlar possiblity after house move 🫰. Do the 'pro domers'  have a minimum size to recommend ?

 

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I built my own 10'/3m plywood dome on the ground.
Then rebuilt it up on top of a two storey DIY observatory. 

My solution to wind lift was to have disks on top of each of the eight rotation rollers.
If the dome ever lifted it was restrained by the disks overlapping the base ring.
No hold downs to remember or forget.
I used a friction roller and crank to turn my heavy dome.
Don't build a plywood dome unless you are a skilled boat builder.
They leak at the joints! :wink2:

A WHITE fibreglass dome would be preferable to avoid heat gain.
Particularly if you get tempted by solar. Don't go green for appearance!
The GRP temperature will rocket in the daytime for solar!
I was building a green 14'/ 4.3m GRP dome until recently. Hot!

Get the biggest dome you can afford. 10' minimum for a 6" refractor. Secondhand GRP? Why not?
Refractors and SCTs make most sense with a dome.
Most domes have high walls. Dobs are like looking up from the bottom of a well.

There is nothing quite like knowing you can go out and find everything set up.
Switch on and start observing and/or imaging.
This lets you do far more of it. No mental hurdles to overcome.
Sky a bit doubtful? You can go out for a few minutes to try your luck.
If conditions are unsuitable then close up and go back indoors.

A dome is the cosiest observatory. Wear warm clothes if it is cold.
Every astronomer should own a duvet jacket.
Get a pair of salopettes for winter from a charity shop.
A good pair of fur lined boots can be quite cheap.
Don't stand on bare concrete or slabs. Put down a mat or rubber tiles.
Sit down if you image. Put a warm cushion on a comfy, patio chair.

Another great advantage of a dome is the hedgehogs can't get at you! :blush:

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On 13/05/2024 at 21:29, Stephenstargazer said:

Following with interest as considering simìlar possiblity after house move 🫰. Do the 'pro domers'  have a minimum size to recommend ?

I find my 2.2 metre Pulsar perfect for the 4" and 4.5"  f7.7 Vixens but a little cramped for my APM 6" F8.  It has to sit very far forward in the mount for me to get behind it with comfort but then of course needs counterweight. This is achieved with a scope on the other side of the AZ100, as well as Rowan's superb Y axis balance plate. It works perfectly well so I am happy.

My AE Luton 4.5" f14 just sticks through the aperture , but since the dome rotation responds to a gentle push with the hand, a little synchronisation and care is all that is needed....:grin:

The Pros of a dome are self evident, the Cons don't need to be regarded as  problems.

If I had a larger garden then the 2.7 metre would have given me more scope....

 

Edited by Saganite
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20 hours ago, Peter Drew said:

Yes.  Domes are never too big, only ever too small.  I have had a self build 9metre aluminium dome for 24 years and we're still short of room!     🙂 

9 metre. Wow, my standard mind quickly visualized 27'!

How tall did that turn out?

Any chance of an image?

I think I could happily set that up for living!

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10 hours ago, tomato said:

I have two 6” refractors side by side in a 2.2 metre Pulsar dome. The aperture is wide enough (just) for these.

 

IMG_1197.jpeg

Is "alien technology" allowed in this thread? :wink2:

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I have to say a double WOW....
Peter the set up and scale at Todmorden is far larger than I had ever envisaged, truly wonderful.
Tomato the double set up looks stunning, shame its for the dark arts 😉 

The 2.2 with the double 150, makes me ponder how much room a visual user would have to observe,
not that a double 150mm set up is ever likely in my case.

This question I posed is actually throwing more queries into the mix than I had considered.

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 The relatively smooth interior of a GRP dome provides rather more cat swinging space. Than any design with interior ribs and a deep base ring.

 I had to give up all hope of a proper dewshield on my 7" f/12 in the 10' dome. The same problem at the tail end. When the 2" Lacerta solar wedge overlapped the base ring at certain times of the year and modest solar altitudes.

 Raising the mounting of a classical refractor may bring the dewshield arc more concentric with the dome. Worth checking if dome space is at a premium.

 A GEM mounted refractor has a complex, oval aerial sweep. Because it is reversed to each side of the mounting when crossing the meridian. I had to be very careful when carrying out a reverse. Not to hit my imaging desk with the elongated filtration unit of a modified 6" refractor. Fortunately I remained in the dome so could carefully monitor during a  slew. Remote imaging would probably require multiple internal cameras. To avoid cable snagging and obstruction problems.

 Many drive systems cannot cope with manual adjustments to the telescopes. The tracking will be completely lost. Without a reset to the nominated parking position. There are of course expensive mounts which allow manual slews. 

 These are all irritations one would never realise without direct hand-on experience over time. Which is why I was building a 14'/4.3m GRP dome. To have more room than the 10' dome provided.
 

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The chap I bought the dome from was visual, he had a 9” SCT on the same pier, there was plenty of room to move around inside with that set up. A big refractor or newt with its corresponding CW bar will inevitably take up more room.

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25 minutes ago, tomato said:

A big refractor or newt with its corresponding CW bar will inevitably take up more room.

That is one of my concerns, the 4" refractors should be ok, but a 10" Newtonian may prove a challenge.
Clearly reason enough for grounds for a 5" refractor at least I think 😉

 

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