# # Program information file # PROGRAM_ID 2021B125 PROGRAM_TITLE Improving SN Ia IR K-Corrections for Dark Energy, Peculiar Velocities, and the Hubble Constant PROGRAM_INV1 David Rubin PROGRAM_INV2 PROGRAM_INV3 PROGRAM_INV4 PROGRAM_INV5 PROGRAM_SCICAT extra-galactic PROGRAM_ABSTRACT_BEG Type Ia supernovae [SNe Ia] are intrinsically superior standard candles in the rest-frame NIR. NIR observations are thus key to many large photometric SN cosmology programs, including RAISIN on Hubble, Hawaii`i Supernova Flows with UKIRT, and the future Nancy Grace Roman SN survey. However, spectroscopic followup has not kept pace with these large photometric surveys. Thus, K-corrections remain uncertain due to both the limited number of spectra available [as only ~ 25 SNe have six spectra or more over their entire phase range] and the calibration uncertainties of the available spectra [many of which do not have simultaneous NIR imaging for calibration]. We thus propose to build out this sample, paying particular importance to calibration. For this semester, we propose following four SNe with a series of six spectra [one every three days] with IRTF SpeX. To obtain enough S/N for the derived K-corrections for each spectrum to be below 0.01 magnitudes, we require S/N of ~ 25 per prism resolution element. For a typical redshift of 0.02, SNe Ia in this phase range will be 16--17 magnitude in J, so this S/N is achievable with SpeX in less than an hour under typical conditions. PROGRAM_ABSTRACT_END