A fast empirical method for galaxy shape measurements in weak lensing surveys
Abstract
We describe a simple and fast method to correct ellipticity measurements of galaxies from the distortion by the instrumental and atmospheric point spread function (PSF), in view of weak lensing shear measurements. The method performs a classification of galaxies and associated PSFs according to measured shape parameters, and corrects the measured galaxy ellipticites by querying a large lookup table (LUT), built by supervised learning. We have applied this new method to the GREAT10 image analysis challenge, and present in this paper a refined solution that obtains the competitive quality factor of Q = 104, without any shear power spectrum denoising or training. Of particular interest is the efficiency of the method, with a processing time below 3 ms per galaxy on an ordinary CPU.
Keywords
Cite
@article{arxiv.1203.4429,
title = {A fast empirical method for galaxy shape measurements in weak lensing surveys},
author = {M. Tewes and N. Cantale and F. Courbin and T. D. Kitching and G. Meylan},
journal= {arXiv preprint arXiv:1203.4429},
year = {2012}
}
Comments
8 pages, 6 figures. Metric values updated according to the final GREAT10 analysis software (Kitching et al. 2012, MNRAS 423, 3163-3208), no qualitative changes. Associated code available at http://lastro.epfl.ch/megalut