ISEN-ASTC-L is a service of the Association of Science-Technology Centers
Incorporated, a worldwide network of science museums and related institutions.
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Well, the product may be new, but the concept is not. This concept was
pioneered by Pittsburgh's Buhl Planetarium and Institute of Popular Science.
Buhl's 10-inch Siderostat-type Refractor Telescope was dedicated as part of
Buhl's "People's Observatory" on 1941 November 19:
< http://buhlplanetarium2.tripod.com/ >

First light through the "Siderostat" was the planet Saturn. The keynote
address at the dedication was delivered by well-known twentieth century
astronomer Harlow Shapley. Buhl Planetarium was the first to use such a
telescope arrangement for public observation, in a museum setting.

From your description, the only difference I can discern with your new
telescope, from Buhl's Siderostat, is that the projection screen is actually
part of the telescope equipment. With Buhl's Siderostat, the solar image was
projected onto a large circular projection screen [which included two
drawings of the Earth, to compare the size of the solar image to the size of
Earth when using a 65 power eyepiece and an 80 power eyepiece] a few feet
away from the eyepiece.

So, we always had to make sure that no one was on the observing platform
[used at night so people could look at celestial objects, by looking through
the telescope] when the Sun was being projected through the telescope. In
your case, it seems that the projection screen is at the end of the
telescope equipment set-up.

From your message, it seems that the solar image is projected onto a
translucent screen, that is viewed by the public from the side of the screen
opposite the telescope. This kind-of set-up is certainly feasible.

HOWEVER, YOU NEED TO MAKE SURE THAT THIS TRANSLUCENT SCREEN NEVER DEVELOPS
ANY HOLES [EVEN MINISCULE HOLES], OR THAT ANY PARTICULAR AREA OF THE
TRANSLUCENT SCREEN BECOMES MORE TRANSPARENT DUE TO AGE OR ABUSE. IN BOTH
CASES, THE BRIGHT SUNLIGHT FROM THE TELESCOPE COULD, THEN, SHINE DIRECTLY
INTO THE EYES OF MEMBERS OF THE OBSERVING PUBLIC. THIS COULD CAUSE EYE
DAMAGE, DEPENDING ON HOW CLOSE THE VIEWING MEMBER OF THE PUBLIC IS TO THE
PROJECTION SCREEN.

gaw

Glenn A. Walsh
  Electronic Mail - < [log in to unmask] >
  Internet, World Wide Web Sites -
  History of The Buhl Planetarium and Institute of Popular Science,
Pittsburgh:
  < http://www.planetarium.cc >
  History of The Adler Planetarium and Astronomy Museum, Chicago:
  < http://adlerplanetarium.tripod.com >
  History of Astronomer and Optician John A. Brashear:
  < http://johnbrashear.tripod.com >
  History of Andrew Carnegie and Carnegie Libraries:
  < http://www.andrewcarnegie.cc >
  The Duquesne Incline, historic cable car railway, Pittsburgh:
  < http://www.incline.cc >

>From: Christine Shupla <[log in to unmask]>
>Reply-To: Informal Science Education Network
><[log in to unmask]>
>To: [log in to unmask]
>Subject: solar telescopes
>Date: Fri, 16 Jan 2004 15:31:31 -0700
>
>ISEN-ASTC-L is a service of the Association of Science-Technology Centers
>Incorporated, a worldwide network of science museums and related
>institutions.
>*****************************************************************************
>
>It isn't a heliostat, but we've just purchased a solar telescope from John
>Welsh at Scopin' USA
>http://www.scopinusa.com/
>
>He's developed it himself, and there's no way for anyone to hurt their eyes
>using it to look at the Sun; the Sun is projected inside of the telescope
>onto a screen that's several inches across and can be viewed by a small
>group together.  Sunspots can be measured, and the image can be traced on
>light paper.  Very affordable, and fairly new (he hasn't started
>mass-production yet.)  Great for a small portable program.  (The only way
>you could hurt someone is by picking up the telescope and swinging it at
>them.)
>_______________________________________
>
>Christine Shupla
>Planetarium Director
>Arizona Science Center
>(602) 716-2078
>[log in to unmask]
>
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