Is NGC 7243 an open star cluster?

Our investigations of the open cluster NGC 7243 aim at answering the question, whether this object is a single open cluster, a double cluster, or only a group of bright stars without any physical connection. Based on the concentration of bright stars on the POSS we have defined two possible field centres. In a first step we have performed number counts using USNO A2.0 and GSC catalogues in two 10' x 10' subfields around the two possible cluster centres in comparison with one neighbouring field. The number of stars in the possible cluster regions do not exceed the number of field stars significantly. Furthermore, we plotted colour magnitude diagrams for the two possible cluster regions, but again no evidence for a star cluster was found. Proper motions were calculated using data from different catalogues ranging from 1902 to 1996, which were reduced with reference stars from Hipparcos and alternatively from the ACT catalogue. No typical cluster concentration was found in the plot of the proper motions for the complete field (1^circ x 1^circ). Only the reduction with ACT provided hints on the existence of a small open cluster. In adition we examined the proper motions of stars within radius of 10' and 20' around the two probable cluster centres, but again no significant cluster concentration was seen. We conclude that, if NGC 7243 is really a star cluster, it consists of only a few members. Further CCD observations are planned to investigate more accurately the colour magnitude diagram of the cluster regios.