An ACS Survey of Globular Clusters V: Star Catalog for Each Cluster

TL;DR

This paper presents a detailed description of a uniform star catalog for 65 globular clusters obtained through HST imaging, including the data processing software and artificial-star testing methodology, to support future scientific studies.

Contribution

It introduces a sophisticated automated software pipeline for star detection and measurement in globular cluster images, ensuring uniform data reduction and analysis.

Findings

Created a homogeneous star catalog for 65 globular clusters

Performed extensive artificial-star tests (~10^5 per cluster)

Enabled future scientific investigations with publicly available data

Abstract

The ACS Survey of Globular Clusters has used HST's Wide-Field Channel to obtain uniform imaging of 65 of the nearest globular clusters to provide an extensive homogeneous dataset for a broad range of scientific investigations. The survey goals required not only a uniform observing strategy, but also a uniform reduction strategy. To this end, we designed a sophisticated software program to process the cluster data in an automated way. The program identifies stars simultaneously in the multiple dithered exposures for each cluster and measures them using the best available PSF models. We describe here in detail the program's rationale, algorithms, and output. The routine was also designed to perform artificial-star tests, and we run a standard set of ~10^5 tests for each cluster in the survey. The catalog described here will be exploited in a number of upcoming papers and will eventually be made available to the public via the world-wide web.