Hard to tell from the bottom angle,
but my guess would be a Buckeye butterfly.

It's an older, faded American lady. Buckeyes don't have the big 'eyes' on their undersides, just the topside - spring form buckeyes show one small 'eye' on their forewings, underside, and the fall/winter form doesn't show any 'eyes' at all, at least on the underside.
Sherry

Thanks butterflyman and Sherry. I believe Sherry is right and we are beginning to see more of the Painted (or American?) Ladies.
Gopal

Butterfly season is just getting started....should see many more soon...