Handbook for the GREAT08 Challenge: An image analysis competition for cosmological lensing

TL;DR

The GREAT08 Challenge is an image analysis competition aimed at improving techniques for measuring galaxy shapes affected by gravitational lensing, which is crucial for understanding dark energy and gravity.

Contribution

This paper introduces the GREAT08 Challenge, a new benchmark for testing and advancing image analysis methods in cosmological lensing research.

Findings

Progress in shape measurement techniques for gravitational lensing

Recognition of the need for statistical inference and machine learning methods

Establishment of a community-wide challenge for method comparison

Abstract

The GRavitational lEnsing Accuracy Testing 2008 (GREAT08) Challenge focuses on a problem that is of crucial importance for future observations in cosmology. The shapes of distant galaxies can be used to determine the properties of dark energy and the nature of gravity, because light from those galaxies is bent by gravity from the intervening dark matter. The observed galaxy images appear distorted, although only slightly, and their shapes must be precisely disentangled from the effects of pixelisation, convolution and noise. The worldwide gravitational lensing community has made significant progress in techniques to measure these distortions via the Shear TEsting Program (STEP). Via STEP, we have run challenges within our own community, and come to recognise that this particular image analysis problem is ideally matched to experts in statistical inference, inverse problems and computational learning. Thus, in order to continue the progress seen in recent years, we are seeking an infusion of new ideas from these communities. This document details the GREAT08 Challenge for potential participants. Please visit http://www.great08challenge.info for the latest information.