MIRI LRS slitless prism data of an unresolved point source observed during the JWST Cycle 1 phase. Left: one detector row selected to examine how the MIRI BFE impacts the LRS PSF (red horizontal line). Top right: raw pixel voltage integration ramps of the pixels sampling the PSF (solid lines) The loosely dashed lines are the nonlinearity corrected ramps. The horizontal black line at 56 600 DNs shows the saturation value for the MIRI LRS pixels. Center right: sampled PSF estimated from two sets of frame differences. 1D Voigt fits to the sampled PSFs are overplotted. Bottom right: LRS PSF FWHM estimated by taking subsequent frame differences along the length of the linearized ramps and fitting 1D Voigt profiles.