These are examples of “dither-synchronous” artifacts, which exhibit periodic signals consistent with the ≈120 s period of the MIS dither pattern. The time bins are 30 s and flux units are counts per second within a 17.″5 aperture, with 3σ error bars. The thumbnail images are 5′ across; the circles in the thumbnails are just graphical indicators, not photometric apertures. Examples A and B show “edge” reflections. Examples C–G are all bright sources triggering nonlinear response in the detector. Examples H–J show a variety of dither-like modulations on low signal or noise. Examples K and L are examples of unmasked hotspots in the FUV detector.