JWST Photometric Time-Delay and Magnification Measurements for the Triply-Imaged Type Ia "Supernova H0pe" at z = 1.78

Supernova (SN) H0pe is a gravitationally lensed, triply-imaged, Type Ia SN (SN Ia) discovered in James Webb Space Telescope imaging of the PLCK G165.7+67.0 cluster of galaxies. Well-observed multiply-imaged SNe provide a rare opportunity to constrain the Hubble constant (H_0), by measuring the relative time delay between the images and modeling the foreground mass distribution. SN H0pe is located at z=1.783, and is the first SN Ia with sufficient light curve sampling and long enough time delays for an H_0 inference. Here we present photometric time-delay measurements and SN properties of SN H0pe. Using JWST/NIRCam photometry we measure time delays of Δ t_ab=-116.6^+10.8_-9.3 and Δ t_cb=-48.6^+3.6_-4.0 observer-frame days relative to the last image to arrive (image 2b; all uncertainties are 1σ), which corresponds to a ∼5.6% uncertainty contribution for H_0 assuming 70 km s^-1 Mpc^-1. We also constrain the absolute magnification of each image to μ_a=4.3^+1.6_-1.8, μ_b=7.6^+3.6_-2.6, μ_c=6.4^+1.6_-1.5 by comparing the observed peak near-IR magnitude of SN H0pe to the non-lensed population of SNe Ia.