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Eruliaf

Obs on garage roof - Great solution, or silly idea?

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I have a nice sized garden and agreement from my wife for a fixed observatory to be placed within, however I have several large trees surrounding my garden which prevent views of large sections of the sky (South, South West, West, North West, and North!). When up on my garage roof the other day, I noted that the view was significantly better than anywhere in the garden, as this is to one side and clears a lot of the trees. (this is part of the house, with a flat roof).

So my question is, has anyone tried putting a observatory in a similar location to this or would the vibrations from walking around cause significant issues with astro photography? Is there a way to prevent this, other than having the pier go through independently to ground level (and through the middle of the garage!) ? Are there issues with a pier this length (say 3m)?

My other thought is to fully automate this so access is only required when setting up, but the cost of this may prevent it for now.

All input welcome!

Thanks

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My first question would be : What is the roof construction ? Will the roof support the weight ? Will the roof cause thermal currents ?

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I have a fourteen feet high, isolated pier to a raised observatory dome.
Naturally I did not want any obstruction on the ground floor.
So I built a simple, four sided pyramid out of 4x4s. [100x100.]

The top half is clad in plywood for stiffness but open below.
The legs are splayed out at ground level to avoid obstruction.
Though the angles are very unlikely to suit a single garage.
Not if you want to park a normal car in there.
A double garage could have a chimney block pier in the middle.

Walking on a wooden floor will disturb a telescope very badly.
When I accidentally shorted out the isolation of my pier from the floor it was hopeless.
Every movement was amplified. Even using a keyboard or mouse.

Then there is the matter of safe access to your observatory.

Nor do you want a block or brick wall below the telescope soaking up the sun's heat all day.
Only to let it escape again right in the path of your optics.

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I think you would need a very substantial support structure for the garage roof if the pier was to be mounted off that. It’s not just the weight, it is making it completely rigid and immune from vibrations.

However, if you are like lots of other people who don’t actually put their car in the garage, I don’t think there would be a problem with an extended pier from the garage floor level. Just make the fixings flush with the floor so you could unbolt the pier and return the garage floor to original condition should you ever need to do so. The pier dimensions and design would need to be sufficient to to prevent flexing given its extended height.

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Just out of interest. Would you need any sort of building regs or planning permission for something like this? 

 

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Quote

Just out of interest. Would you need any sort of building regs or planning permission for something like this? 

That's what I was wondering apart from the other queries mentioned above.

I wouldn't have thought you could get permission for a wooden built construction attached to the house/garage.

As regarding vibration from walking, well at worst you are going to waste 1 sub at each end of the imaging session if you can walk away and leave it running, then access it from the comfort of the house via a remote computer.  That's what I do anyway once it is up and running.

Carole 

 

 

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Worth considering if it was a choice between astronomy or no astronomy, but for imaging , a chainsaw would be a cheaper option.   😀

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Thanks for the input.

The trees are not in my garden, so the chainsaw is not an option - well not if i want my neighbours to ever talk to me again!

I think I have to rebuild the garage due to it falling away from the house, therefore when I reconstruct it, it can be designed to accommodate any necessary modifications to allow for the observatory on top. Access (believe it or not) can be from the house, which for some reason has a door at first floor level onto the flat roof next to the garage.

I was thinking of a frame within the garage (think 'n' shape) with a fixing in the middle through the roof for the pier, so you can still use the garage - however I think you are correct in that this may all be scuppered by planning, unless of course it became a 'temporary' structure.

I think I will have a look to see what is covered by permitted development, as otherwise this could quickly become a very expensive idea.

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I wonder what they would say about a dome on the garage roof, or does that look too obvious for potential thieves?

Another thought is what type of roof will you have on it?  Was thinking about the extra length needed for roll off.

Carole 

 

 

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My gut tells me you'll need to go through planning, time consuming and expensive.

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The remote control aspect has been discussed and is highly desirable to avoid footfall vibration under these special circumstances.

A Pulsar is light, as observatories go, but would need a very sturdy [plywood?] floor bolted down to the garage roof to resist gales.
I'd probably avoid a dome altogether and have a roll-off shelter for the telescope and mount only. Guyed to avoid wind problems.
Then you can raise a windbreak around the perimeter of the garage roof to hide it all.

If you don't have to literally get under a short refractor to look up through the eyepiece then the whole kit can all be very low indeed.
Just enough clearance for a camera to swing above the garage roof with the OTA at the vertical.
Park the thing with minimum height in mind for designing the weatherproof box.

Or, carry the whole kit in and out of the door onto prepared marks on the garage roof for minimum impact. Store the kit safely indoors.
It's not as sexy as a "real" observatory but you don't need one for imaging. Observatories are horribly cold and draughty. Nasty! 🥶

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The biggest problem with constructing an observatory anywhere near a large structure is the turbulent air that will run around the observatory. You can reinforce the structure to support the weight of the observatory, you can make a pier that is isolated from the vibrations of the structure but it will be insanely difficult to  isolate the whole structure from releasing the heat into the surrounding air. I did the following "experiment" and I invite you to do the same: 

On 3 nights with good seeing I moved my mount between the south facing balcony, 30 feet from the house on a concrete pad that was covered with a bath rubberized carpet and 400 feet from the house in the middle of the garden. I took my time and I did the polar align within 1 arcmin and I guided a short refractor for an hour at each location. I made sure that the mount was in all 3 locations at the same hour between the nights. The results were: 

On the balcony RMS between 0.7 and 1.2 arcsec RMS

At 30 feet from the house between 0.5 and 1 arcsec RMS

At 400 feet from the house between 0.3 and 0.7 RMS

Also good to remember that I have a Class A energy efficient house that does not output a lot of its heat in the environment. 

The best thing to do is to find a solution to "shave" the trees. 

Edited by mihaighita
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I have an issue with trees and the fact my garden drops about 25 feet over its length. I have accepted that there's no point looking north as it's toward Manchester that way and light pollution rules out anything worthwhile. Towards the house and uphill is the best sky looking south, east and more or less west. There are a lit of trees and I cannot see anything below a 30 degree angle on the scope. However, even in these circumstances I feel an obs is worth it as I can access more objects than I'll ever get bored with and will not be (or should not be) affected by affected by local lights and will therefore have better quality of opportunity. I'd reconsider whether or not the patch of sky visible would be worth it to you.

Here's my (in progress) obs

IMG_20190922_152221.thumb.jpg.895e9c6e3fc2572fbd6f82ef72f5e4a2.jpg

IMG_20190914_183533.thumb.jpg.5813d8526d3784faf780e2a5f59372f0.jpg

 

 

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PS I like trees and think there's a balance between a garden to enjoy and maximising observing.

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28 minutes ago, Moonshane said:

PS I like trees and think there's a balance between a garden to enjoy and maximising observing.

Do you mean like this?  That is my two storey observatory looking west.

House is on the southern border to the left.

 

P1390211 obs trees.JPG

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Yep totally. I think sometimes we obsess about getting as low in declination as possible but for visual observers in light polluted areas surrounded by houses there's often no point. Higher in the sky is darker and more stable. I have decided to accept my (somewhat self imposed) circumstances and make the best of it. 👍

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Based on the permitted development (well, my understanding of it), I think I could get away with it, but to avoid objections/irate neighbours I need to try to get it to blend in.

A dome makes it obvious (to most people) what it is and therefore would be a target - not to mention expensive. A wooden shed would look hideous and massively out of place on the roof. So, current thoughts are for a low profile brick built square with hinge off roof (avoids the need for additional supports of a roll off), however I don't think I could automate that - but would always need to get to it to take lens covers off etc anyway. I can ensure the redesign of the garage can accommodate this by incorporation of some steels to the roof, aligned with the wall locations. 

The more I think about it, the more I am leaning towards making the back of the garage almost dual height (well, 1.5x) with internal steps to access it (like a glorified garage loft). Another advantage of this is that, if insulated well it could effectively be internal unless in use, keeping it warmer and dry and can also be secured internally. This seems to be growing legs....

On the plus side, I can easily extend the alarm to cover the obsy to protect it.

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Not an easy task to have access from below and maintain fire safety rules, weatherproofing and insulation.
I have the same idea in my two storey observatory using a huge, aluminium, warehouse stepladder.
The trapdoor is an absolute nuisance in the observatory floor. I would never recommend anything similar.
But I wanted to avoid wintry climbs in the dark. So chose an internal ladder for access.
Don't use an ordinary ladder because of serious safety issues. You get no feedback for balancing on narrow rungs.
You need wide treads and comfortable lean angles for when you are carrying kit up and down. And you will.

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Is this for visual or imaging?

If for imaging, couldn't you reduce the footprint of the 'obsy' and install a powered extendable pier? Open the lid, hit the button and the pier extends to imaging height.

There is a thread on here somewhere with one of the piers shown. (On way to work shortly so not got time to search).

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If for imaging I would consider a dedicated mini-obsy on the roof. Completely remote.

There is a thread here somewhere....ill take a look... of someone who built a remote obsy to go on a balcony. Very compact and a slightly bigger one would probably house the 130 on an EQ5.

Edit: heres the one I was thinking of:

 

Edited by upahill

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On 23/09/2019 at 16:09, Moonshane said:

I have an issue with trees and the fact my garden drops about 25 feet over its length. I have accepted that there's no point looking north as it's toward Manchester that way and light pollution rules out anything worthwhile. Towards the house and uphill is the best sky looking south, east and more or less west. There are a lit of trees and I cannot see anything below a 30 degree angle on the scope. However, even in these circumstances I feel an obs is worth it as I can access more objects than I'll ever get bored with and will not be (or should not be) affected by affected by local lights and will therefore have better quality of opportunity. I'd reconsider whether or not the patch of sky visible would be worth it to you.

Here's my (in progress) obs

IMG_20190922_152221.thumb.jpg.895e9c6e3fc2572fbd6f82ef72f5e4a2.jpg

 

 

 

Ugh. Sorry for being so direct, but while you have a very beautiful garden and the Obs is looking to be a beauty, personally, I don't see the point what with all the high flora at every turn. And I thought my views in my backyard were obscured almost beyond hope (by neighbor's very tall trees - full southern sky blocked, etc), it only goes to show that things can always be worse. And I have a really big yard! I have in the past considered building an observatory, but mainly as a place to store my scopes for easier access to the yard (as opposed to in the basement). The trees blocking my astronomy efforts preclude any kind of fixed observation enclosure for me. It would be counterintuitive. But, to each there own and I wish you the best and clear skies!

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I purchased a scope I think from Bornemouth way. The chap told me to look for the obs on the garage...Yes he has put a dome on his flat roof and had a door at the top of his stairs for access and a massive steel tube running down through the roof to the floor to mount the scope. This tube actually when through his utility room.

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