2021JAVSO..49..192H

Globular clusters are an ideal laboratory for studying and comparing variable stars, since all the variables in a globular cluster formed from the same progenitor gas cloud. Because of this, all of the variables within a given cluster have similar ages, metallicities, reddening, and distances from Earth. Thus we estimated the age, metallicity, reddening, and distance of the clusters NGC 5272, NGC 1904, NGC 3201, and Terzan 3 by doing a visual fit to isochrones. Knowing the characteristics of these clusters as a whole helps us better understand the characteristics of individual variables in these clusters as well. Reddening, metallicity, and age estimates for NGC 1904 and NGC 5272 are consistent with previous literature, but all four of the estimated parameters for Terzan 3 and the metallicity measurement of NGC 3201 differed significantly from literature values. Further research into NGC 3201 and Terzan 3 is recommended.