Unknowns after the SNO Charged-Current Measurement

We perform a model-independent analysis of solar neutrino flux rates including the recent charged-current measurement at the Sudbury Neutrino Observatory (SNO). We derive a universal sum rule involving SNO and SuperKamiokande rates, and show that the SNO neutral-current measurement can not fix the fraction of solar $\nu_e$ oscillating to sterile neutrinos. Even when we impose the SSM $^8$B flux constraint, the sterile neutrino fraction remains essentially undetermined.