Excelsior had a reputation as one of the top mirror makers in the US, before closing their doors some years ago. I managed to get a 10" F6 mirror which had primarily been used for planetary work.
There are no figures available for this mirror but there are a few things I know about it.
Focal ratio: F6
Mirror substrate: Pyrex
Coatings: Spectrum
I have centre spotted the mirror (crudely, but effective)
There is a 1/4" band of adhesive black flocking placed around the edge of the mirror by the previous owner to reduce the effects of a very slightly down-turned edge.
The mirror is dusty but can obviously be cleaned
The coatings are in good condition
I paid US$500 for it, yours for AU$325 or best offer
Check out this URL for pricing
http://home.no.net/jonbent/reflectors.htm
Regards
10" F6 Excelsior Mirror
