Photometric UBVI CCD photometry is presented for NGC 188 and Berkeley 17. Color-magnitude diagrams (CMDs) are constructed and reach well past the main-sequence turnoff for both clusters. Cluster ages are determined by means of isochrone fitting to the cluster CMDs. These fits are constrained to agree with spectroscopic metallicity and reddening estimates. Cluster ages are determined to be 7.0+/-0.5Gyr for NGC 188 and 10.0+/-1.0Gyr for Berkeley 17, where the errors refer to uncertainties in the relative age determinations.
Cone search capability for table J/AJ/131/1565/table2 (NGC 188 Photometry)
Cone search capability for table J/AJ/131/1565/table3 (Berkeley 17 photometry)