Research-grade CCD cameras can develop "bad columns" over their lifetime. While Telescope Live has mitigated this issue by transitioning to CMOS cameras, older datasets - of which there are thousands - might still exhibit these bad columns. Cosmetic correction addresses these and other issues, like hot and cold pixels. Dr. Ron Breacher from Masters of PixInsight will guide you through the Cosmetic Correction tool, ensuring your images are refined before stacking.