Searching for RR Lyrae variables in the Second Data Release of the NOAO Source Catalog

RR Lyrae are periodic variable stars with periods of less than one day. They can be used as standard candles for accurate distance measurements and thus are useful for studying the structure of the Milky Way and stellar clusters. The second data release of the NOAO Source Catalog (NSC DR2) is a large collection of 68 billion time-series measurements of 3.9 billion objects. To process such large amounts of data, we are designing a pipeline to automatically detect variable stars in the catalog and measure their properties including their period, mean magnitude (in multiple bands), and the amplitude of their variability. We explore the advantages and disadvantages of various photometric variability metrics such as a chi-squared test against the mean value, the interquartile range, and the von Neumann ratio in detecting RR Lyrae variables. Once candidates are selected, we will fit templates to their light curves to categorize them and obtain more refined measurements of their period, magnitude and amplitude. With our final catalog of bona fide RR Lyrae, we plan to map the stellar structure in the outer Milky Way, especially in the southern hemisphere, which has not yet been well explored.