ComEst: a Completeness Estimator of Source Extraction on Astronomical Imaging

Authors: I-Non Chiu, Shantanu Desai, Jiayi Liu

ComEst is a completeness estimator of CCD images conducted in astronomical observations saved in the FITS format. Specifically, ComEst is designed for estimating the completeness of the source finder SExtractor on the optical and near-infrared (NIR) imaging of point sources or galaxies. The completeness is estimated as the detection rate of simulated sources-- simulated by the python image simulation toolkit GalSim-- which are injected into the observed images with various configuration. In this way, ComEst estimates the completeness of the source detection-- as a function of flux (or magnitude) and, moreover, position on the CCD-- directly from the image itself. ComEst only requires the observed iamge as the input and performs the end-to-end estimation of the completeness. Apart from the completeness, ComEst can also estimate the purity of the source detection.

ComEst is released as a Python package with an easy-to-use and flexible syntax. More information can be found in the paper.

If you use ComEst in your work please contact the authors.

Installation

1. Download ComEst.

2. To Install ComEst one simply types

   python setup.py install
   

   If you dont have the permission to install, you can instead type

   python setup.py build
   

   and then add the library (i.e., build/lib) to your PYTHONPATH.

3. To run ComEst one needs the following prerequisites.

• Numpy

• SciPy

• PyFITS

• GalSim

• SExtractor

  ComEst is tested against numpy > v1.9.1, SciPy > v0.14.0, PyFITS > v3.3, GalSim > v1.3 and SExtractor > v2.19, although ComEst should work with the older versions of prerequisites. Since ComEst heavily relies on GalSim, we strongly recommend that users should install GalSim with version higher than v1.3.

4. The installation is done. Now you can load in ComEst package by typing the following in python environment

   import comest
   

Documentation

Please see here.

Acknowledgement

This work is dedicated to Chien-Ho Lin in Taiwan.

We acknowledge the support by the DFG Cluster of Excellence "Origin and Structure of the Universe", the DLR award 50 OR 1205 that supported I. Chiu during his PhD project, and the Transregio program TR33 "The Dark Universe". The computations for ComEst have been have been carried out on the computing facilities of the Computational Center for Particle and Astrophysics (C2PAP) and of the Leibniz Supercomputer Center (LRZ).

Contribution

Any comment and suggestion is welcome, please email to inonchiu@usm.lmu.de, shantanu@usm.lmu.de or Jiayi Liu.