SIMBAD references

Photometric monitoring of the central 17'x17' of the old open cluster NGC 188 with the WIYN 3.5 m telescope has resulted in the discovery of a number of new variable stars, down to 21.5 mag in V, 35 of which have well-determined periods. The variability types of the fainter stars of the sample (18-21.5 mag) remain uncertain. However, most of the brighter stars (15-18 mag) probably make up the low-luminosity extension of the already known W UMa population of NGC 188. We also report the discovery of two longer period variables on the subgiant branch of the cluster CMD, most likely FK Comae stars, which suggests that the cluster may provide significant insight on the formation and evolution of contact binary systems. Alternatively, these objects may represent a new kind of pulsation variables.