The neutron star mass plotted vs. the asynchronicity factor 1 − β₀ for the 7 binary systems listed in Table 5. Synchronously-rotating optical components lie at 1 − β₀ = 0. Error bars are the uncertainties quoted by the authors listed in Table 5. A trend for more massive neutron stars with larger departures from synchronicity is observed. Whether this indicates a systematic error in the mass determination due to tidal effects is an open question that requires a larger sample of systems before a firm conclusion may be drawn.