Searching for Variable Stars in Globular Star Clusters

Indianapolis, IN

By using the Southeastern Association for research in Astronomy (SARA) telescope located in Cerro Tololo, Chile, we were able to search and detect variable stars located in the globular clusters IC4499, NGC5824, and NGC6723. For about ten nights throughout the months of May, June, and July, we obtained the images of each cluster specified above. After each night of observing, we would process each image using the Maxim DL program. After each image was properly formatted, we would use the ISIS 2.2 image subtracting program to align, stack, and subtract each image out of a created reference frame. This would allow the program to detect and find which objects in the images were varying. A light curve data file would then be fit to each varying object that had been detected. We would then use a simple Python Script to plot each light curve. Once each curve was created we would then manually go through each curve to in order to pull the real stars from just image defects. We would then check each star with a previously detected star chart to see if it was newly discovered. Each cluster produced a different number of newly discovered variable stars.