  In modeling the potentials of quadruply lensed quasars, investigators often
employ models for the stellar surface brightness profile of the lensing galaxy
for the sole purpose of eliminating its contamination of the light from the
quasar images and their hosts. When the center of that profile is used, it is
usually as a weak prior on the center of the potential. But the central maxima
in the light from single lensing galaxies lie closer the centers of the lens
potentials than has heretofore been thought. New measurements are presented
here of the positions of the compact central regions of lensing galaxies
observed with the Hubble Space Telescope. Comparing these with modeled
positions for the centers of the lensing potential (constrained only by the
positions of the four quasar images) we find agreement consistent with the
larger of either our measurement uncertainties or 1% of the radius of the
Einstein ring.
