We present a homogeneous survey of the CN and CH bandstrengths in eight Galactic globular clusters observed during the course of the Sloan Extension for Galactic Understanding and Exploration ( SEGUE ) sub-survey of the SDSS .
We confirm the existence of a bimodal CN distribution among RGB stars in all of the clusters with metallicity greater than [ Fe/H ] = -1.7 ; the lowest metallicity cluster with an observed CN bimodality is M53 , with [ Fe/H ] \simeq - 2.1 .
There is also some evidence for individual CN groups on the subgiant branches of M92 , M2 , and M13 , and on the red giant branches of M92 and NGC 5053 .
Finally , we quantify the correlation between overall cluster metallicity and the slope of the CN bandstrength-luminosity plot as a means of further demonstrating the level of CN-enrichment in cluster giants .
Our results agree well with previous studies reported in the literature .