Revised Feb 5th, 2022 Recently I noticed that, in my narrowband astrophotos, the red color of the stars in my calibrated LIGHT frames seems shifted a few pixels. The blue pixels are also shifted but by a much smaller amount. I decided to invent a visualization tool for CaLIGHTs that makes it easy to study this color shift. In CaLIGHTs V3.1.6 I introduced a feature called SatGuard. This feature requires CaLIGHTs to be able to identify bright stars and determine what pixels need to be modified. I had already created…