I worked on this FITS image someone posted about an artifact in the lower right corner ... by putting it into "ImagesPLus" and using the "Stretch" as 'Digital Development' and setting the 'Breakpoint' and then the top HDR Stretch area you use the 'nth Root' option and it's 'Root' slider to reveal more outer area . Then "Multipoint Flatten Background" , and "Levels" with the "Process History" 'Mask' for the 'multi-point mask' to conceal the galaxy and darken the outer background with the 'Black' in the "Levels" command .
