Finding RR Lyrae Stars with SkyMapper: an Observational Test

TL;DR

This paper evaluates the SkyMapper Survey's effectiveness in detecting RR Lyrae stars, demonstrating over 90% completeness with a three-epoch observation strategy and exploring methods to distinguish RR Lyrae populations.

Contribution

It provides an observational validation of the survey's efficiency in identifying RR Lyrae stars and introduces a gravity-sensitive diagram for better population separation.

Findings

Over 90% recovery rate of known RR Lyrae stars with the survey strategy

Effective boundaries identified in the gravity-sensitive diagram for high completeness and efficiency

Demonstrated the usefulness of the diagram in separating stellar populations

Abstract

One of the major science goals of the SkyMapper Survey of the Southern Hemisphere sky is the determination of the shape and extent of the halo of the Galaxy. In this paper we quantify the likely efficiency and completeness of the survey as regards the detection of RR Lyrae variable stars, which are excellent tracers of the halo stellar population. We have accomplished this via observations of the RR Lyrae-rich globular cluster NGC 3201. We find that for single epoch uvgri observations followed by two further epochs of g, r imaging, as per the intended three-epoch survey strategy, we recover known RR Lyraes with a completeness exceeding 90%. We also investigate boundaries in the gravity-sensitive single-epoch two-color diagram that yield high completeness and high efficiency (i.e., minimal contamination by non-RR Lyraes) and the general usefulness of this diagram in separating populations.