(Proposal ID) S16A-178 (PI) Doi, Mamoru (Proposal Title) Testing for Time-Varying Dark Energy with z>1 Type Ia Supernovae (Abstract) A key goal of observational cosmology is to constrain the nature of dark energy through the detailed, accurate and unbiased measurement of the expansion history of the Universe. The SNe Ia luminosity-distance relation is determined by the dark energy density evolution, rho_{DE}(z). The existing ground-based z<1 sample place strong constraints on rho_{DE}(z) out to z~1. To confirm dark energy at z>1 and test the new BAO results, it is necessary to use SNe Ia at 11.3 SN Ia which will be observed by HST ToO orbits to guarantee at least two colors. This is a continuation of S15B-141 program. We have completed 44% of the survey and found 11 z>1 SNIa candidates as we had forecasted, and we expect to continue to discover high-z SNeIa to be followed in S16A semester.