Group reads for a stationary field star (top) versus for a serendipitously detected numbered asteroid 417988 (bottom). Images are taken from JWST PID 5594. These images contain a ramp of N = 4 groups. The pixel scale of each cutout is 0﹩\mathop{.}\limits^{{\unicode{x02033}}}﹩031 pixel^–1. The default ramp fit assumes a stationary source, whereas a moving source will cause the slope in each pixel it transits to be underestimated when compared to the asteroid’s true flux rate.