Program: GN-2011B-Q-68

The Carnegie Supernova Project~II (CSP~II) is an NSF-funded, 5-year program to obtain optical and near-IR (NIR) observations of 100--150 Type~Ia supernovae (SNe~Ia) located in the smooth Hubble flow ($0.03 < z < 0.08$). The main emphasis of the CSP~II is to obtain NIR light curves in order to achieve a distance precision of 1$-$2\%, as well as to build a definitive low-$z$ reference for future rest infrared observations of SNe~Ia at high-$z$ with next-generation dark energy experiments such as WFIRST. A key ingredient to realizing these goals is the measurement of NIR $K$ corrections as a function of light curve phase and shape, which to date are only poorly understood. We therefore request 100 hours of ToO time over 5 years with GNIRS on Gemini North to obtain multi-epoch NIR spectroscopy for $\sim$25 of the SNe to be observed by the CSP~II. In this first proposal, we ask for a total of 10~hours to obtain spectra at two different phases of 2--3 SNe.