Program: GS-2009B-Q-11

We have found an unexplained diversity in the UV spectra of intermediate redshift Type Ia supernovae (SNe Ia) which may arise from variations in progenitor metallicity. To understand the implications and any redshift-dependent biases in the use of SNe Ia for measurements of dark energy, we are undertaking a new HST ToO program from July 2009 - June 2010 to gather UV spectra of 35 local SNe Ia, taking advantage of two new local "rolling'' transient searches. Our sample also will be unique in having continuous photometric/spectroscopic coverage from early phases (LCOGT, Lick, Palomar, Keck, HET, VLT). Here, we seek to exploit the rapid ToO mode of Gemini N and S to obtain the required very early-phase confirmation spectra for candidates in 2009B, essential to the success of this program, providing the classification upon which targets can be scheduled at HST. These rare early-phase spectra will also offer new opportunities in studying SNe Ia and their progenitor compositions.