Re: [ATM] Celestron 20" R-C telescope

["Stuart Hutchins" <stuart452@earthlink.net>]

Serrurier trusses for amateur visual use don't compute, even for "go to"
systems.  Especially for "go to" systems, because mounts errors can be
calibrated out, and a couple of arcminute accuracy puts the target in the
eyepiece.  The biggest problem is the squishy stuff that you set the scope
up on.  There are a lot of cow patties in the National Forests of Colorado.

For imaging systems, you have to do guiding anyway, so that feedback
mechanism compensates for any reasonable structure deflection that changes
during long exposures.

Stuart


----- Original Message ----- 
From: "Thomas" <tomjan@ozemail.com.au>
To: "'Stuart Hutchins'" <stuart452@earthlink.net>; "'ATM'" <atm@atmlist.net>
Sent: Tuesday, May 04, 2004 4:10 PM
Subject: RE: [ATM] Celestron 20" R-C telescope


> Yeah I noticed that too, on the face of it, IT sounds like a Serrurier
> system, but the pics don't really look like one. Maybe they just wanted
> the "big scope truss look" and a convenient CG as well?
>
> Clear skies,
> Thomas Janstrom
> http://www.tjanstrom.com
> http://www.norsewines.com.au
> "Your nobody untill you've been ignored by your seventh cranio-facial
> nerve."
>
>
> -----Original Message-----
> From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net] On Behalf
> Of Stuart Hutchins
> Sent: Wednesday, 5 May 2004 6:47 AM
> To: ATM
> Subject: Re: [ATM] Celestron 20" R-C telescope
>
>
> After seeing the Anacortes pictures (link provided by Michael), this
> does not look like a Serrurier structure.  Notice the Dec shaft appears
> to go into the center of the lower truss, not the rings between the
> upper and lower.  It simply looks like a box to connect the Dec shaft.
>
> My, what a lot of metal way up in the air.
>
> Stuart
>
> ----- Original Message ----- 
> From: "Stuart Hutchins" <stuart452@earthlink.net>
> To: <artbianconi@blast.net>; "ATM" <atm@atmlist.net>
> Sent: Tuesday, May 04, 2004 2:17 PM
> Subject: Re: [ATM] Celestron 20" R-C telescope
>
>
> > Art,
> >
> > Serrurier truss?  Linear deflection at the cage equals linear
> > deflection
> of
> > the mirror.  Pointing angle then does not change as the structure
> > sags. http://astro.umsystem.edu/atm/ARCHIVES/JUL95/0114.html
> > http://astro.umsystem.edu/atm/ARCHIVES/SEP03/msg00804.html
> >
> > Stuart
>
>
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>
>
>


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