[Atmob-club] observatory design question

[pbealo at comcast.net]

George,

Interesting questions. I can only address a couple - and those mainly with other questions (how socratic!):

1) The only stable building-mounted scopes I have ever seen were in Munich at the Bavarian Public Observatory (  http://www.lrz-muenchen.de/~t7121bl/astro/vsw_e.html ). Steve Beckwith and I had the opportunity to visit one of their open houses about 8 years ago. Their observatories are built on top of an above-ground WWII vintage air-raid shelter. The walls were easily 3 ft thick concrete and god knows how thick the ceilings were. BTW - this is the only  astro soc "clubhouse" I ever visited that had a permanent bar and beer taps - just a suggestion for the clubhouse committee  :>)   :>)
 Unless you're built on a similar structure, I'd say do not build an observatory on a roof without an isolated pier to ground. You will not know how bad it is until the money's spent and its built.

B) whether or not YOU want to have people on a school roof, what will the school administration or school district say?!?! Will they be willing to make a ruling today that binds them not to change it tomorrow?? They are VERY risk-averse these days. For instance, according to a friend living in Haverhill MA at the time, during the 1994 (I believe) annular solar eclipse, their school district REQUIRED all classrooms in the district to close their blinds. 

KISS: roll off roof at ground level. 

Peter



 -------------- Original message ----------------------
From: "George Roberts" <gr at gr5.org>
>      I'm still trying to get a small observatory built for the local high school 
> - hopefully a rolloff roof design in a field.  However, the whole high school 
> will be rebuilt in about 3 years and this would be an opportunity to put an 
> observatory on the roof.  There's a much better view from there.  Access would 
> be easier to control, and getting access to electricity, internet would be 
> easier.  However there would be other issues.
> 
> One of the goals would be to be able to have occasional star parties at night - 
> invite the whole town or invite a class of students.  So we would need to be 
> able to host up to 25 or hopefully even 40 people (limiting to 40 should be 
> fine).  So we would need deck space for "open observing".  So I would still 
> favor a roll-off roof design even on an existing 3rd story roof (strange).
> 
> I'm sure you have comments about this and please do, but my main question is - 
> in a normal modernly constructed steel building - how stable will the roof be if 
> we mount the telescope right on the roof with no separate pier going down 
> through all the floors into the bedrock (like they do at the clay 
> center/southfield/dexter school)?  With 25 people horseing around and walking 
> around will that make the view of the moon vibrate annoyingly?  Or are modern 
> steel (and concrete?) buildings so heavy and strong and stiff that it will only 
> be a minor problem.  And how about when there are only 3 people sitting down 
> calmly observing (which should be much more often)?  At night when the school is 
> relatively empty and quiet?  Also what about when it is more crowded I envision 
> a second or even third telescope setup on tripod on the roof?  I imagine an 
> isolated rectangle of decking so that the tripod isn't resting on the same piece 
> of wood as the people.  Or maybe it will be tar/gravel style roof with no 
> decking.  Has anyone actually tried this?  
> 
> I know Harvard has that telescope on the roof and lots of people can mill around 
> outside the dome on the roof and look at the stars.  Do they ever setup a second 
> telescope on a tripod out on the roof?  Does the view jiggle at all?
> 
> - George Roberts
> 


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