Hubble Diagrams of Type Ia Supernovae in the Near-Infrared

From observations of 7 Type Ia supernovae obtained during the last four years at the Las Campanas and Cerro Tololo Inter-American Observatories, along with previous published data for 9 supernovae, we present JHK Hubble diagrams and derive absolute magnitudes at maximum light of 16 objects out to a redshift of 0. 038. On the scale of H₀ = 72 km/s/Mpc we find mean absolute magnitudes at maximum of -18. 57, -18. 24, and -18. 42 for J, H, and K, respectively, with 1-sigma uncertainties of the distributions of values of +/- 0. 14, 0. 18, and 0. 12 mag. The data indicate no significant decline rate relations for the infrared. Thus, Type Ia SNe at maximum brightness appear to be standard candles in the infrared at the +/- 0. 20 mag level or better. The minimum requirements for obtaining the distance to a Type Ia SN are: reasonably accurate values of Delta m₁5 (B) and T (Bₘax), and one night of infrared data in the -12 to +10 d window with respect to T (Bₘax).