The NIRSpec IFU Point Spread Function

Abstract I provide characterizations of the point-spread function (PSF) of the high-resolution observing mode of the NIRSpec integral field unit on JWST. Using observations of an isolated late-type star, the two-dimensional shape of the star was modeled with concentric Gaussian profiles. The widths and weights of the representative Gaussian components that comprise the PSF model for a variety of drizzle reference frames and final spaxel sizes are presented. The PSF is noticeably elongated, with an axis ratio of ∼0.75. Both elongated PSF models as well as circular approximations to the PSF shape are included. The PSF is generally well-represented by a pair of concentric Gaussians, with ∼75% of the flux contained in a narrow core with a width on the order of a single spaxel, and the other ∼25% of the flux in a more extended halo.