A Good Size

[Colinlp]

I'm in the process of replanning my observatory after the initial plan looked like it would fall foul of the dreaded planning police, so a rethink is needed. At this stage I can't decide if it will be a roll off or a dome

I have a CPC 1100 11" SCT on a fork mount and eventually will be sat on a Celestron HD wedge. My question is twofold, for both types of building what size would be a sensible size without being huge and  what would be the minimum size practical without getting splinters in my rear end from scraping on the walls?

My initial plan was a 10' dome but height is the issue

Thanks

[laser_jock99]

10 foot square is a good size I think- but keep the height to under 2.4m to avoid planning issues.

[ollypenrice]

You're dead sure you want a wedge? Just asking!!

Is this for visual, imaging, or both? You need more room for visual.

Olly

[Colinlp]

Pretty sure at this moment I'll need a wedge, it will be a mixture of visual and imaging I hope.

I think I can get away with 2.7m high with a dome but I'm not sure I can get away with a 10' dome. Currently I'm toying with the idea of a 10 x 8 1.4m high with a rounded end with an 8' dome, even then the scope will need to be quite high in the dome to lower the horizon. I don't think I'll get away with a 10' because it would start a bit close to the wall and I'm sure the neighbour would complain to the council, not that it would affect him in any way as he could only see the top of it from his garage roof but he does go up there once a month to polish it, I kid you not

If it's a roll off I'm 100% stuck with 10 x 8 as there isn't enough room to roll the roof off without making the thing too high, I have 16' to play with.

Is 8' going to be too small? It's been a long time since I was last in an observatory and that was about a 4m dome

[ollypenrice]

Just a thought but with a roll off you can make the roof and upper sides roll, so lowering the fixed wall height. I don't know if this would be any help in your situation but all ours do that. One rolls back over a warm room like this;

Another space saver I've used a couple of times is a pod for PC. Again, whether this might help in your case I don't know.

The breeze block observatory in the first image is 2.2 metres square and would be possible but tight for visual. I'd have thought that a 9 foot dome would be better for visual but could you go and look at some first?

Olly

[Colinlp]

Now that's an interesting one, certainly allow a 10' roll off with that. I've been trying to think of novel ideas even a pop top turret like a rotating campervan top

[nytecam]

Got a sub 6ft dome for my 12" SCT on fork mount - fine for visual but I'm 100% brief exposure real time imaging nowadays:-) Check my build via my links.

[Colinlp]

Got a sub 6ft dome for my 12" SCT on fork mount - fine for visual but I'm 100% brief exposure real time imaging nowadays:-) Check my build via my links.

I've got your observatory build in my favourites, I often look at it, to be honest it's the one thing that keeps me asking these questions! What is the minimum inside diameter of the dome and what do you think would be the maximum height practicable you could place the OTA pivot on the forks and still get your head in without performing some Yoga exercise ?

I will predominantly be visual, at least at the outset but even if I did use it more for imaging the dome would be the only place I could sit as I have no more space for a warm room

[ollypenrice]

Remember that, should you ever move to a GEM, you'll need more space than with a fork. Forks are brilliantly compact.

Olly

Edit; Avalon make single arm mounts which work like forks so you are not limited to the Americans if you do change mount at some time.

[Colinlp]

Cheers Olly, I don't see myself ever changing from the forks but who really knows what happens.

To be honest I'm really leaning towards a split roof roll off at the moment, I see that as being the option with the most personal space, my only real issue is the exposure to dew on electronics such as a PC or paper charts etc. I just still feel a dome would give better protection there as well as having a smaller shadow footprint during the daytime on out BBQ area. Talk about a confused bunny!

[steppenwolf]

I have always found my 7 foot (2.1metre) diameter domed observatory to be more than adequate in size for both observing and imaging (for the former, I use a 250mm aperture Newtonian) and it comes in under the 2.5metre height limit thus obviating the need for planning permission.

[kirkster501]

Guys is that right?  Less than 2.5m and no planning permission required?

[Colinlp]

I'm going to run off a few 2.4m rings out of MDF on a CNC and mock up a dome I think, it's the only way I'm going to find out for sure

[Colinlp]

Guys is that right?  Less than 2.5m and no planning permission required?

Less than 2m away from a boundary wall it has to be less than 2.5m. Further than 2m it can go up to 4m if it has 2 pitched sides and no upstairs but has to be 2.5m max to the eaves

[steppenwolf]

Less than 2m away from a boundary wall it has to be less than 2.5m. Further than 2m it can go up to 4m if it has 2 pitched sides and no upstairs but has to be 2.5m max to the eaves

I concur

[ollypenrice]

I'm sure you're right about domes being far better defenders against dew. I never had the bottle to try to make one!   Maybe I should, but I ran out of swear words during the relatively simple task of making rectangular roll offs so a dome would have rendered me mute in no time, and that would never do!!!

Olly

[Gina]

I've often though I'd like to make a dome but like Olly, found a ROR shed hard enough.  I did consider it for my mini obsy for widefield imaging but currently settled for a cylindrical roof.  I may yet make a domed mini obsy as the cylindrical one is far from finished.  If I can manage to make up a fork mount for it and thereby reduce the size needed, I might just have a go.  But don't ask me which year that might be, I have far too many projects on the books already

[Colinlp]

I guess I'm lucky in that most of my working life I was a cabinet maker so making things isn't really the issue, it's getting the comprimise right in this case. I'll try and make the rings for the false dome tomorrow and then have a go with them over the weekend to see how they pan out with the scope and me inside them. At least that way I can finally say yes or no to size and design options

[kirkster501]

Less than 2m away from a boundary wall it has to be less than 2.5m. Further than 2m it can go up to 4m if it has 2 pitched sides and no upstairs but has to be 2.5m max to the eaves

Great!  Will put a call into the planning guys as a precaution to see what they say.

[Colinlp]

Great!  Will put a call into the planning guys as a precaution to see what they say.

Check this out:

http://www.planningportal.gov.uk/permission/commonprojects/outbuildings

[Colinlp]

Got my rings made on Friday and put together a mock up of an 8ft dome. With the help of a couple of wheely bins that elevated the dome to just about the right hight in proportion to the scope there would appear to me more than enough room. The good news is that with a bit of playing around I can if I use an 8ft square base just about squeeze 2m away from the boundary wall which gives me the freedom to go higher. The top of the scope can sit level with the top of the grey roof in the picture (if I've got the upload right, it's the first time I've used it), that will be plenty high enough to safely get as low a view as is practicable.

So, as long as my wife doesn't feed me anymore pies I think we have a solution

[Colinlp]

A week on from this and I'm wondering if a roll off roof would be better, of more convenient for stuff like space for a PC or somewhere to write. Anybody got any thoughts that may help me?

[Beulah]

Do you really have to have a dome? And where are you planning to put the obs? That summerhouse structure looks like a perfect place to have an observatory with a ROR, warm room, the works - and as it's already there, there would be no need for planning permission. My guess is that the Summerhouse is well used, and it won't go down too well if you replace with a ROR Observatory!

Nice bit of garden, BTW....

[Colinlp]

The summer house is just that, getting drunk and BBQing is a religion in our household so it's an essential building LOL, I suspect my voice would raise in pitch several octaves if I suggested using that!

There used to be a pond  there which has been filled in (mostly with rubble) but that's where it has to fit which isn't a lot of room which is why a dome seems to make sense. I had considered building a dome on top of the little workshop to the left but that would definitely call for planning permission which the neighbours directly ahead would object to (miserable sods!). Anyway getting as high as I can with the proximity on the buildings is what I need to do but still to keep it as low as possible. But no a dome isn't essential, I'm just concerned about dew affecting electronics or papers but I have no benchmark to judge how much of a problem it might be in a roll off

[Gina]

A roll off roof observatory with a small warm room is best IMO.