ATM Mirror/Foucault readings

[Bob Hazel <machead@qadas.com>]

I posted a message about two weeks ago about a central hill on my
mirror that didn't seem to want to polish out. Well, what I have tried
is this. I used the cordal stroke a little, was kinda afraid to do it
too much. I also ordered new pitch and made a new lap. Spent most of the
polishing sessions with MOT. Well, after 5-6 readings with the foucault
tester this is what it is telling me as far as ROC for the different
zones. (Don't laugh or I'll tell my mom!)
Zone 1: 96.875"
Zone 2: 96.880"
Zone 3: 96.852"
Zone 4: 96.850"
Zone 5: 96.860"

  this is for an 8" mirror. I'm no expert, but from what I read, isn't a
sphere supposed to be the same ROC from center the edge? And a parabola
supposed to have a LONGER ROC from center to edge? This is getting very
frustrating. Do I keep polishing with TOT to get back to sphere?

  Thanks.

bob-Denver,CO