ComEst: A completeness estimator of source extraction on astronomical imaging

The completeness of source detection is critical for analyzing the photometric and spatial properties of the population of interest observed by astronomical imaging. We present a software package ComEst, which calculates the completeness of source detection on charge-coupled device (CCD) images of astronomical observations, especially for the optical and near-infrared (NIR) imaging of galaxies and point sources. The completeness estimator ComEst  is designed for the source finder SExtractor  used on the CCD images saved in the Flexible Image Transport System (FITS) format. Specifically, ComEst  estimates the completeness of the source detection by deriving the detection rate of synthetic point sources and galaxies simulated on the observed CCD images. In order to capture any observational artifacts or noise properties while deriving the completeness, ComEst  directly carries out the detection of simulated sources on the observed images. Given an observed CCD image saved in FITS format, ComEst  derives the completeness of the source detection from end to end as a function of source flux (or magnitude) and CCD position. In addition, ComEst  can also estimate the purity of the source detection by comparing the catalog of the detected sources to the input catalogs of the simulated sources. We run ComEst  on the images from Blanco Cosmology Survey (BCS) and compare the derived completeness as a function of magnitude to the limiting magnitudes derived by using the Signal-to-Noise ratio (SNR) and number count histogram of the detected sources. ComEst  is released as a Python  package with an easy-to-use syntax and is publicly available at https://github.com/inonchiu/ComEst.