[Atmob-club] observatory design question

[George Roberts]

     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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