Re: ATM where can I purchase a 12.5" f/20 mirror

["Bob May" <bobmay@nethere.com>]

The basic direction of this list is to go build it yourself.
Starting with a fairly flat piece of glass, you can start the grinding at
320 grit as the depth of the center of the mirror is going to be only about
.040"
The biggest problem will be finding out how good the surface is as you will
be looking at a piece of glass that is about 40' away and that will mean
using a telescope to see what the results are.
Being that it is a spherical surface that you really need, the making of the
final polish won't be that hard as your figuring that will need to be done
will be towards making the easy sphere rather than the much more difficult
parabola.
Don't forget that you're also going to be needing to make a large flat also
to direct the light to that mirror and that will be a bit more difficult
than the spherical surface.
If you really don't want to do this yourself, consider putting an ad in the
local paper for somebody to grind and polish a mirror for you and you will
probably get a few responses.
Bob May
http://nav.to/bobmay
bobmay@nethere.com
NEW! http://bobmay.astronomy.net