  We present phase resolved optical spectroscopy and X-ray timing of the
neutron star X-ray binary EXO 0748-676 after the source returned to quiescence
in the fall of 2008. The X-ray light curve displays eclipses consistent in
orbital period, orbital phase and duration with the predictions and
measurements before the return to quiescence. Halpha and He I emission lines
are present in the optical spectra and show the signature of the orbit of the
binary companion, placing a lower limit on the radial velocity semi-amplitude
of K2>405 km/s. Both the flux in the continuum and the emission lines show
orbital modulations, indicating that we observe the hemisphere of the binary
companion that is being irradiated by the neutron star. Effects due to this
irradiation preclude a direct measurement of the radial velocity semi-amplitude
of the binary companion; in fact no stellar absorption lines are seen in the
spectrum. Nevertheless, our observations place a stringent lower limit on the
neutron star mass of M1>1.27 Msun. For the canonical neutron star mass of
M1=1.4 Msun, the mass ratio is constrained to 0.075<q<0.105.
