We present CCD UBVI photometry of the nearby, intermediate-age open cluster NGC 6939. Using the synthetic colour-magnitude diagram technique we estimate the following parameters: age between 1.3 and 1.0 Gyr (depending on whether or not overshooting is considered), reddening 0.34 <=E(B-V) <= 0.38 and distance modulus 11.3 <= (m-M)0<= 11.4.
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- February 2004
- Hertzsprung-Russell (HR) diagram;
- open clusters and associations: general;
- open clusters and associations: individual: NGC 6939;
- 11 pages, 10 figs, MNRAS in press. Revised version correcting mistakes in comparison with Twarog et al. (1997) in Sections 1 and 5, kindly pointed out by B. Twarog