Variable Stars in the Field of the Open Cluster NGC 7789
  Fifteen variable stars have been discovered during four nights of monitoring of NGC 7789. It was possible to determine periods for ten of these variables. Seven objects are W UMa-type binaries, in this number five are members of the cluster. Among the remaining variables, there are three further close binaries, one delta Scuti which is a Blue Straggler in the cluster, and one multi-modal variable (with indeterminable periods). One of the binaries showed an eclipse-like event; this binary is a good candidate for determination of masses of its components at the turn-off point of the cluster. 
K. Jahn, J. Kaluzny, and S. M. Rucinski