The dual channel Pierce-Blitzstein photometer (PBPHOT) was productively used at the Flower and Cook Observatory to provide 60 years of study of binary systems and other cosmic objects. We review the history of this instrument, discuss its calibration, and recall some personal and professional interactions with Professor Robert H. Koch.

• Carol Ambruster(Villanova University)
• Tony Hull( University of New Mexico) | Tony Hull
• Robert H. Koch( ) | Robert H. Koch
• Rich Mitchell( Gravic Inc) | Rich Mitchell
• George Wolf( Missouri State University) | George Wolf
• Bob Smith( University of Pennsylvania) | Bob Smith