This is the fourth paper in a continuing study on the standard photometric signatures of geosynchronous earth orbit, GEO, communication satellites. Here we present the results of photopolarimetric measurements taken at the Air Force Research Laboratory Directed Energy Directorate's Starfire Optical Range.. These limited set of measurements were conducted in order to determine if GEO communication satellites have measurable polarization, and is so, if there are differences between the satellites. Measurable polarization was detected. This polarization was seen throughout the night varying smoothly from a minimum at local midnight, approximately 10%, to a maximum at dawn of approximately 40%. This is distinctly different from the radiometric signals which is a maximum at local midnight and decreases toward dawn and dusk. This polarization is found to be distinct for each GEO satellite bus. Also, serendipidously it is found that when measuring through cirrus clouds, the photopolarimetric signal is not lost, although it is changed.