SIMBAD references

New B, V, and I CCD photometry is presented for the intermediate-age open cluster NGC 6939. V, B-V and V, V-I color-magnitude diagrams (CMDs), which extend 4 mag fainter than previous CMDs, have been constructed. The CMDs show a clearly defined turnoff and well-populated red giant clump, suggesting a cluster age of at least 1 Gyr. A comparison between the clump stars of this cluster and those of the open cluster NGC 752 indicate a color excess and distance modulus of 0.33±0.07 and 12.27±0.41 mag, respectively. Examination of reddening maps and CMDs of different quadrants of the cluster suggest that variable reddening across the face of the cluster is present. Color excess values and distance moduli for four quadrants of the cluster range from 0.29 to 0.41 mag and 12.21 to 12.39 mag. Comparison between the V, B-V CMD and solar metallicity isochrones yield a cluster age of 1.6±0.3 Gyr.