Planets in stellar clusters extensive search. I. Discovery of 47 low-amplitude variables in the metal-rich cluster NGC 6791 with millimagnitude image subtraction photometry

We have undertaken a long-term project, the Planets in Stellar Clusters Extensive Search ( PISCES), to search for transiting planets in open clusters. As our first target, we have chosen NGC 6791 a very old, populous, metal-rich cluster. We present the results of a test observing run at the F. L. Whipple Observatory's 1.2 m telescope. Our primary goal is to demonstrate the feasibility of obtaining the accuracy required for planetary-transit detection using image subtraction photometry on data collected with a 1 m class telescope. We present a catalog of 62 variable stars, 47 of them newly discovered, most with low-amplitude variability. Among those there are several BY Draconis type variables. We have also observed outbursts in the cataclysmic variables B7 and B8.