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Published online by Cambridge University Press: 12 April 2016
CCD’s have made possible the extension of intermediate-band photometric systems, including the Strömgren uvby system, to larger, fainter and cooler stars, with successful applications in old disk and globular clusters. Some of the applications in globular clusters demonstrate the ability to remove foreground stars from photometric diagrams and have enabled a re-evaluation of the evolutionary correction needed for distance modulus determination for metal-poor stars. We have developed an additional index based on measurement of the Ca II H and K lines which retains sensitivity to metallicity changes for extremely metal-poor stars. Finally, we are testing the utility of CCD H/β photometry in the unusual and old open cluster Melotte 66.