[Atmob-discuss] observatory dome versus roll-off - looking foradvice

[Steve Beckwith]

George,

I have a self-built dome similar to Mario's.  The similarities don't end
there as I agree with his opinion on accessibility and going with a
roll-off.  I have a sixteen-foot dome and can only comfortably fit six
adults in it - eight in a pinch.   Little things such as only one or two
people at a time in a dome can really limit or kill the long-term interest
of the teachers and students.  I've found with most things (gadgets,
etc.)usability is important.  If something is tough to use or access, then
people will lose interest.

 

- Steve

 

 

-----Original Message-----
From: atmob-discuss-bounces at atmob.org
[mailto:atmob-discuss-bounces at atmob.org] On Behalf Of Mario Motta
Sent: Wednesday, December 05, 2007 2:11 PM
To: George Roberts
Cc: atmob-discuss at atmob.org
Subject: Re: [Atmob-discuss] observatory dome versus roll-off - looking
foradvice

 

Hi George,

 

  As you know I stronly favor domes, so my advice might seem unusual, but
clearly not biased. For your school project a roll off makes the most sense.

first, buying a small 10 foot dome would be a major error. You will only fit
a few students at a time, could not have a group viewing without lots of ina
nd out activity. Small domes only make sense for remote observing or
individual observers. 

A large dome bought would be prohibitively expensive for your budget, and
take some skill to build properly from scratch.  Still have problem of large
crowds in the dome.

A roll off allows best use., most students have never seen the sky well, let
alone view through a scope. this allows general sky viewing, allows large
classroom size crowds in the viewing area and not allow a buildup of heat
ruining observing. For wind, place barriers than can be raised on either
side. 

Personal viewing, I strongly prefer a dome.

My thoughts,

Mario Motta

 

On 12/5/07, George Roberts <gr at gr5.org> wrote: 

My local High School started an Astronomy club (cool!) as I've mentioned
earlier.  And now they want to build an observatory.  Currently the 
budget is $3k for observatory materials and $3k for telescope + camera,
accessories etc.  We plan to get a 10 inch cassegrain.  We have a
funding source (and can probably get more $ if we have to) and I'm
working on getting permission for a location but I wanted to ask about
observatory designs.  The Industrial Technology teacher is an
experienced, licensed carpenter and wants to have his students build it
over many months inside the H.S. Garage (lots of space and huge garage
doors) and then final assembly out on the fields.  So I have free labor
and some expertise.  The extra labor to make geodesic isn't an issue.
The whole thing would be designed in their cad software down to every 
detail - different students could concentrate on different parts of the
design.

My question is about various designs.  We have looked at dome versions
and roll-off versions.  I have always leaned to roll off.  It seems to 
me roll-off is simpler but the IT teacher thinks a geodesic dome would
be better.   I guess he likes the idea of making a zillion triangles.
So can some of you please give me opinions and ideas as to both methods? 

Some thoughts:
Dome blocks the wind which is a big bonus.  I've heard about
condensation problems as dew forms inside and drips down if it is a thin
dome.  Explora dome makes a beautiful one piece polyethylene dome for 
$1100 shipped (8 foot diameter) (google explora dome to see it).

Roll-off has advantage of seeing the sky with your eyes and not just the
telescope.  Doesn't need cooling fans.  You don't need to have everyone 
duck under the doorway to get in and out (once the roof is off).  Easier
to build maybe because no curves?

In either case we would have concrete footings, a concrete pier
(separate from floor vibrations) and the IT class would make a wedge out 
of thick steel plates (they love desinging this kind of stuff).  Maybe I
can get the IT instructor to come visit the club's roll off plus
someone's dome.

- George Roberts
http://gr5.org

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