Determining the high energy neutrino flavor ratio at the astrophysical source

We discuss the reconstruction of neutrino flavor ratios at astrophysical sources through the future neutrinotelescope measurements. We demonstrate by a statistical method the accuracies required in the measurements of energyindependent ratios R and S, where R is the number ratio between track and shower events. For energy below a few PeV, shower events consists of electron and tau neutrino events. However, for energies beyond, a tau-lepton behaves like a track similar to a muon. This motivates a new classification of event types and new definitions for R and S. We present our analyses in both types of measurements, R and S, at corresponding energy regime.