Variable stars in the field of open cluster NGC 6939

@article{Maciejewski2007VariableSI,
  title={Variable stars in the field of open cluster NGC 6939},
  author={Gracjan Maciejewski and Ts. B. Georgiev and Andrzej Niedzielski},
  journal={arXiv: Astrophysics},
  year={2007}
}
The results of CCD photometric survey performed with the 90/180 cm Schmidt-Cassegrain Telescope of the Nicolaus Copernicus University Astronomical Observatory in Piwnice (Poland) and the 70/172 cm Schmidt Telescope of the National Astronomical Observatory (NAO) at Rozhen (Bulgaria) of the field of 1 Gyr old open cluster NGC 6939 are presented. Twenty two variable stars were detected, four of them previously known. Four eclipsing systems (3 detached and 1 contact binary) were found to be members… 

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