PSR J102347.6+003841 is a radio pulsar system with a spin period of 1.69 ms and an orbital period of 4.75 hours. Uniquely, it undergoes periods of transient accretion from its companion star: it occupies an important position in the evolutionary trac
k from X-ray binary to isolated millisecond radio pulsar. Here we present a spectroscopic study of this system showing late-type absorption features which match those of a G2V star. We find a semiamplitude of $286 pm 3$ kms$^{-1}$ and a best fit orbital period of 0.1980966(1) days. We combine these measurements with optical photometry which suggests the secondary star may be underfilling its Roche lobe by between 15% and 20%. We weakly constrain the mass of the neutron star to be $leq$ 2.2 M$_odot$ at the 2$sigma$ level. We also discuss the possible origins of the H$alpha$ emission line in our template subtracted, averaged spectrum. Finally we present and discuss new optical photometry of J1023 taken during the recent outburst of the system.
