Re: [ATM] Stone observatory foundation?

["Don D'Egidio" <djd521@comcast.net>]

Michael,

Our club uses a roll off roof observatory that is 14'X24' and has concrete floors with plastic sheeting under the gravel to prevent water from wicking into the interior. The walls are 11' tall and made of cinder block, originally for an 8" refractor.

We painted the exterior with a special heat reflecting white paint used by the swimming pool industry. It is designed to be painted on concrete surfaces near pools so you feet won't get burnt when the concrete is in direct sunlight. The inside temperature tracks the outside to within 2-3° F, even when the outside temp went to 103°F. Once the roof is opened at night, it only takes about 30-45 minutes before the inside and outside temp is equalized. I usually use that time getting setup for a nights observing. There are many ventilation holes on the roof eaves and a ridge vent on the roof.

Here is a link to a few pictures of the observatory. http://dvaa.org/Photos/ColonialObservatory/

Building the observatory higher because of some local trees restricting your horizon will only buy you a few years at best. The trees will grow and soon the horizon will be the same as if you built the observatory at ground level. Weigh the added expense and effort of building higher against loosing that advantage in a few years as the trees grow. If the trees are on your property it might be better to have them pruned to improve your horizon.

Some suggestions for the roof track, use an upturned angle iron welded to some flat stock and then grooved wheels on the roof. That provides a self centering rolling system and also self cleans snow and ice. When our observatory was designed they used flat wheels on a flat track. Also make sure your pier is isolated from the concrete floor.

Good luck on building your observatory.

Don

----- Original Message ----- 
From: "Michael Burr" <mtburr@msn.com>
To: "ATM list" <atm@atmlist.net>
Sent: Saturday, March 19, 2005 10:19
Subject: [ATM] Stone observatory foundation?


Greetings:

I haven't posted in a long time; my ATMing has been dormant over the past year while I have concentrated on building our new house. But in the wake of a recent visit by John Dobson, I'm inspired to take up the task again.

One of the projects I have planned is to build an observatory. I'm considering raising the observatory up, maybe 6 feet or more, to get a little more clearance over some trees that border my location. There are a lot of small boulders strewn around, and I am considering building the raised "base" of the observatory from stone and concrete. I am unsure, however, of the thermal properties of stone. I would not want to create a radiative nightmare.

I've searched the ATM list archives and done some poking around on the web, but thus far haven't found any useful guidance. Does anyone on the list know whether stone soaks up and radiates a lot of heat? I'm guessing it does and I am out of luck with it.

Unfortunately I don't know what kind of stone it is. We have a lot of granite around here (central Minnesota) and if I had to guess I'd say maybe it's granite. Definitely it's not a sedimentary rock. It looks metamorphic to me.

Any thoughts would be welcome.

Best Regards,
Michael Burr
_______________________________________________
ATM mailing list http://www.atmlist.net/


_______________________________________________
ATM mailing list http://www.atmlist.net/