A new differential variable-star photometry system has been designed, constructed, and tested at the Rothney Astrophysical Observatory of the University of Calgary. The system uses a single telescope, photometer, and detector and consists of gated pulse-counting electronics synchronized to a chopped secondary mirror. The mirror is driven to four positions, permitting rapid alternate detection of a variable star, comparison star, and two sky-background regions. Within certain constraints the system is insensitive to the effects of transparency, sky-brightness, and detector-sensitivity variations occurring on time scales longer than the system’s duty cycles. The system has proved effective under as much as three magnitudes of cloud and attendant sky-brightness variation.
© 1982 Optical Society of America
Original Manuscript: March 25, 1982
Published: August 15, 1982
E. F. Milone, R. M. Robb, F. M. Babott, and C. H. Hansen, "Rapid alternate detection system of the Rothney Astrophysical Observatory," Appl. Opt. 21, 2992-2995 (1982)