New Photometric System for CN and CH

During the last decade, there has been a dramtic paradigm shift on the definition of the globular cluster (GC) systems. The decades-long lighter elemental variation issue in GC stars is now considered to be a generic feature of normal GCs in our Galaxy, most likely engraved during the multiple-phase normal GC formation. In this talk, we will introduce the new photometric system, so-call the JWL System, to measure CN and CH abundances in multiple stellar populations in GCs. The utility and the future application of the JWL System will be discussed.