Astrophysically Relevant Examples of Relativistic Image Doubling

Relativistic image doubling (RID) is an unusual effect where relativistic motion causes particles, shadows, and illumination fronts to appear doubled. RID effects occur all around us every day, but on human scales occur so fast they are difficult to notice. Recent refereed publications have demonstrated that RID might also occur and be detectable in gamma-ray bursts, cosmic ray air showers, and water-based Cherenkov detectors. RID effects might also be evident in astronomical light echo systems including sources with moving shadows and in the reflections of a stellar flash from a gas or dust disk. RID effects, if found, potentially encode information about a system that was not previously available. Finding useful astrophysical RID effects may involve pushing the boundaries of high time-resolution and short-cadence data-taking and imaging.