Alan, is this a recognized Overton or a new discovery? I don't know why, but I have the gut feeling this might end up being an R5 or rarer.
Doesn't look as an "O" to me. Looks more like an eye. Has two rings and a funny looking center, as a iris of an eye.
I sure wish this was the case.....but its not. The coin is an 1833 O-103 R2, the picture of the O-103 marker in Peterson's book has the same double circle. I'm not sure what it is or was. Its a little too late for that, its already part of my collection. I collect Capped Bust Half Dollars by die marriage, could care less if I ever sell any of my Bust Halves, so AT/NT really has no bearing to me. Its amazing to me that you can tell its AT from a microscope photo.