This long-focal-length, full-thickness Pyrex mirror has quality written all over it (not literally!) Sourced from a hi-tech Raytheon optical facility, it's in excellent condition in every way and comes mounted on a very nice 3-point adjustable optical mounting (probably worth a few hundred by itself). Everything about its appearance speaks of a laboratory-grade, EXPENSIVE piece of glass.
I examined its Ronchi images at ROC and included below a representative 'in & out' snapshot. The surface is nice & smooth, with a good edge and only a very slight deviation near center (mostly covered by the secondary, I would think). Being no optical expert, I asked our local optical guy his opinion - he felt that its curve was biased somewhat towards a sphere, but at f/10 he said it didn't make much difference...it should provide nice diffraction-limited images.
So consider giving this unique mirror a good home - it's a rare find. I'm asking $775 OBO plus shipping (it's really solid!). PayPal acceptible (you cover the fee), or other payment arrangements as necessary (M.O., etc.)
This baby is nice...believe me (see my ratings). Thanks for looking & Clear Skies!