Re: ATM Why siderostat is not popular - YES

["B. Pepin" <atmjedit@conceptsnet.com>]

Hi Xuandong,

Heck, I love siderostats! I have built 40mm f/7, 50mm f/12, and 70mm f/12
versions of a portable tracking and slewing unit (to be published in ATMJ
17-18 when that dual issue comes out)

Am currently *finishing* the design of a 102mm f/15 polar mirror siderostat,
to be used for solar work in conjunction with a new-design filter wheel and
filter-mount carriage. The biggest problem is a really FLAT flat, and
*accurately* pointing that flat given the doubling of errors on angle of
incidence.

If you have an interest in this kind of work please reply on or off list --
siderostats are very cool!

Barlow

----- Original Message -----
From: <xuandong@public6.sta.net.cn>
To: <atm@shore.net>
Cc: <iss@pvtnetworks.net>; <roedder@roedder.com>; <westland@ust.hk>
Sent: Sunday, July 22, 2001 5:55 AM
Subject: ATM Why siderostat is not popular


>
> I think that a siderostat can greatly simplify the mount system of large
> focal-ratio telescopes. But to my surprise, I've never seen any large
> focal-ratio telescopes, whether made by professionals or amateurs, that
> use siderostat (except the solar tower telescopes).
>
> After searched keywords of "heliostat or coelostat or siderostat" in the
> archive of http://astro.umsystem.edu/atm/, I only found few articles
> that shortly mentioned siderostat, such as:
>
> > Subject: Re: ATM A Very Long Newtonian
> > From: iss@pvtnetworks.net
> > ...
> > Actually, a siderostat feeding a long f# mirror gives you
> > a stationary eyepiece, the problem is getting low enough
> > air turbulence in the horizontal optical path...
>
>
> Why siderostat seldom be used? Have you seen any web sites
> that detailed discuss the pros and cons of siderostat?
>
>
> Thank you.
> Andong Xu
>