Roll off roof obsy...a fundamental decision to be made
Hello fellow astro dudes!
I'm making a pretty basic, 1 room roll off roof observatory. It will have a gable roof on rollers. The rollers and rail are pretty darn heavy duty. They cost me about 5k (already bought them) and can hold 1500kg each bearing (there are 4).
I'm thinking it'll probably be about 20 square meters plus an outside paved area for visual. I have a lot of space (rural location) so footprint is no concern. Cost however is.
I have a fundamental decision to make: should I make the walls high enough to be able to close the roof without putting the scope in a horizontal position (see photo attached), or should I make the walls shorter, enabling the building to be smaller dimension overall? I would like to view targets 15 degrees or so from the horizon (what are people's thoughts on this? Is this too much to ask or too little?).
My pier, mount and current scope (only a 100mm APO refractor) is 2100mm tall. I'm hoping to eventually replace it with a 12.5 or even 14 inch planewave CDK. So I'd need it to be even taller, or else I'd need to put the pier on a lower footing than the flooring. Any advice would be greatly appreciated, as this is the first thing I've ever made, and my builder, although an absolute legend and expert, has never made an obsy before. Thanks in advance!!!
Have you seen Willy Kortz roll off roof and portal frame observatory. Kind of complicated but a cross between a roll away portal frame shed and a roll off roof is possible. So the walls can be lower. The message is that the walls and the roof can join at any height you choose..The roll off roof can incorporate some part of the wall height.
To don’t mean that you should build a complete rolling portal frame, just the idea that the walls and roof can overlap at different heights to allow a view to the horizon.
Hi Franco, (I saw your message but will reply here for ‘knowledge bank’ reasons.
I my opinion 15’ is pretty low on the horizon and you really will be battling plenty of additional atmosphere to capture those photons. Personally I won’t go any lower than 27’ when imaging.....30’ is my preference.
As for where to park your scope - I’ve actually set up a custom park position on mine that sees the RA more or less horizontal and the DEC pointing down at around 75’. I do this so when my imaging runs finish the scope can be automatically parked in a position that won’t allow dust to settle on the front lens meaning there is no need for a cap.
You asked about waterproofing in the message - basically my roof hangs over and is lower than the walls....that is all that is needed to keep the water out.....it doesn’t go uphill hahahaha. If you are concerned about dust I’d be using that continue brush material that is used as a weather seal on doors.
You also asked about having the end walls fold down - one end of mine does (north) and one doesn’t (south). I’ve never been faced with an issue of not being able to image because of this....you are only blocking a very small amount of sky when you take into account earth rotation.
If I was you I would be working out the highest point your scope will be and then add a little safety margin....this should be your roof pitch height.
Remember though that making a shorter pier from scratch will be much cheaper than building a higher ob’s to fit an existing pier in.......just my thought.
Thanks for the reply! You're right...anything less than 25 degrees isn't crash hot for photography but I want to at least be able to, particularly for interesting visual stuff in the future. But also, I don't want to feel like I'm in a cage when I'm inside the obsy. It would be cool to be able to look at the landscape as well. Furthermore, I'd like to be able to use my old mount as well (Eq6r) which is a lot shorter than my new ASA mount/1200mm pier combo. As for the pier, I got it specifically made for my new setup so I won't be getting another even though it's pretty tall.