  Integrated ground-based and HST optical studies of isolated neutron stars
have provided important independent datasets in the determination of emission
activity, particularly in the fitting of anticipated Rayleigh-Jeans
extrapolations from EUV/soft X-ray datasets, despite their intrinsic faintness.
Differentiation of the pulsed and unpulsed fluxes and consequently of the
nonthermal and thermal modes of emission could provide definitive data with
which to constrain this blackbody continuum. Based upon high speed photometric
observations of Geminga and PSR B0656+14 in the B band, we have combined upper
limits of unpulsed emission with recently published model-fits with a view to
assessing possible implications for the R/d parameter. For Geminga, with a
known distance of ~ 160 pc, we find that R_{infty} < 9.5 km for a ~ blackbody
source, and R_{\infty} < 10.0 km with the presence of a magnetized H
atmosphere. In addition, we suggest that PSR B0656+14 is some ~ 4 - 5 times
closer than the 760 pc estimated from DM measurements alone.
