Observatory Design Questions

[Fuddsy]

I am attempting to design a fairly large roll-off roof observatory (for group viewing) and need some basic general questions answered. I hope nothing too technical at this point.
I would be using this as a private facility, invite only for serious and semi-serious users.

1) What would the maximum dimensions that could be used in the overall building and the maximum size of the roll-off roof? I am thinking of room for 2 piers and room for 2 Tripod mounted scopes.

2) What is the optimal diameter of the work area surrounding a pier?

3) What is the optimal size of the warm work room, to hold maximum 4 viewers (without sitting on top of one another) and laptops with chairs and couple of file cabinets?

4) What wall height would be the best to accomodate both pier and tripod?

Any and all suggestions good or bad are appreciated.

[KeithBC]

To answer your first question, I don't think there is a maximum size for a roll off roof. At least football stadium size...
Skydome-big.jpg

[skinnyonce]

Once we get done with you,, have you been to cloudynights observatory section,, some keen stuff there to

If you want to play around with a free cad program heres one,, suppose to be google sketchup 8 maybe they changed the name

Trimble SketchUp

[AustinPSD]

You need to start with thoughts around item 2, the work area surrounding the pier.

This is dependent on several factors, including the pier diameter, which is based on the mounting plate and mount requirements for a given telescope. The swept area of the mount head, including counterweight bar, OTA assembly, and desired horizon are also factors. Added to the mechanical aspects of the pier, mount and swept area is the working room for either a seated or standing observer. Depending upon the observatory design, you may also need to include room for a small table or work-surface near the pier/telescope assembly (applies for use of a lap-top/workstation if one is an imager).

For talking purposes, a CGEM mounted on a pier, using an 8" OTA and standard-length counterweight bar sweeps an area approximately four feet in diameter with the assembly pointed roughly five degrees above the horizon. Adding 22" to 30" of room for clearance (the approximate width of a person) gives you a circle roughly six feet in diameter.

Before it makes much sense to answer the remaining questions, you need to think about the specifics of the mount/telescope(s) you are contemplating using. This in turn will dictate wall height, overall room dimensions, etc.

[Bob327]

As Austin noted I'd personally allow 6 foot around each pier (and for any tripods that will be set up inside) so a 16x16 building is the bare minimum but that is going to put each Pier pretty close to two of your walls..so fold down walls would also most likely be needed... The warm room would have to be an addition to the building.. I'd make it at least 20x20 and most likely 24x24

I run a domed obs (10x10 building) so I have less then 5 foot under the dome itself around the pier .. it works fine BUT I use a Alt/Azm mounted forked Sct any Gem mount would make things a little tight in my opinion ..I have had 4 individuals in the obs using the scope it was like playing musical chairs.. everyone had to take one giant step to the right when the observers changed..

You have lots of variables to factor in and I guess a few too many compromises will be required... All I can say is I'mm glad I normally view alone...or with one guest

Bob G.

[Tim K]

Regarding the clearance around the pier, I have to agree with the previous posters. If your plans might involve a GEM and refractor, allow at least a six-foot radius. My observatory only has one pier in a 10'x10' area and there is not much room to move past the scope when it's set up for imaging. Dew shields and camera gadgets add quite a bit of extra length.

Another consideration is conduits for wiring. I often see people using 1/2" or 3/4" conduit for cable runs from the warm room to their pier. It's much better to go oversize and use 3" PVC water pipe for the low-voltage and control cables, and a separate (to meet electrical codes) 1" grey PVC for the AC power lines. As plans change (and they will), it is much easier to remove or pull new cables through the oversize conduit.