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Results of the GREAT08 Challenge : an image analysis competition for cosmological lensing

Bridle, S.; Balan, S.T.; Bethge, M.; Gentile, M.; Harmeling, S.; Heymans, C.; Hirsch, M.; Hosseini, R.; Jarvis, M.; Kirk, D.; Kitching, T.; Kuijken, K.; Lewis, A.; Paulin-Henriksson, S.; Schölkopf, B.; Velander, M.; Voigt, L.; Witherick, D.; Amara, A.; Bernstein, G.; Courbin, F.; Gill, M.; Heavens, A.; Mandelbaum, R.; Massey, R.; Moghaddam, B.; Rassat, Anais; Réfrégier, A.; Rhodes, J.; Schrabback, T.; Shawe-Taylor, J.; Shmakova, M.; van Waerbeke, L.; Wittman, D.

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S. Bridle

S.T. Balan

M. Bethge

M. Gentile

S. Harmeling

C. Heymans

M. Hirsch

R. Hosseini

M. Jarvis

D. Kirk

T. Kitching

K. Kuijken

A. Lewis

S. Paulin-Henriksson

B. Schölkopf

M. Velander

L. Voigt

D. Witherick

A. Amara

G. Bernstein

F. Courbin

M. Gill

A. Heavens

R. Mandelbaum

B. Moghaddam

Anais Rassat

A. Réfrégier

J. Rhodes

T. Schrabback

J. Shawe-Taylor

M. Shmakova

L. van Waerbeke

D. Wittman


We present the results of the Gravitational LEnsing Accuracy Testing 2008 (GREAT08) Challenge, a blind analysis challenge to infer weak gravitational lensing shear distortions from images. The primary goal was to stimulate new ideas by presenting the problem to researchers outside the shear measurement community. Six GREAT08 Team methods were presented at the launch of the Challenge and five additional groups submitted results during the 6-month competition. Participants analyzed 30 million simulated galaxies with a range in signal-to-noise ratio, point spread function ellipticity, galaxy size and galaxy type. The large quantity of simulations allowed shear measurement methods to be assessed at a level of accuracy suitable for currently planned future cosmic shear observations for the first time. Different methods perform well in different parts of simulation parameter space and come close to the target level of accuracy in several of these. A number of fresh ideas have emerged as a result of the Challenge including a re-examination of the process of combining information from different galaxies, which reduces the dependence on realistic galaxy modelling. The image simulations will become increasingly sophisticated in future GREAT Challenges, meanwhile the GREAT08 simulations remain as a benchmark for additional developments in shear measurement algorithms.


Bridle, S., Balan, S., Bethge, M., Gentile, M., Harmeling, S., Heymans, C., …Wittman, D. (2010). Results of the GREAT08 Challenge : an image analysis competition for cosmological lensing. Monthly Notices of the Royal Astronomical Society, 405(3), 2044-2061.

Journal Article Type Article
Publication Date Jul 1, 2010
Deposit Date Mar 21, 2013
Publicly Available Date Feb 19, 2015
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 405
Issue 3
Pages 2044-2061
Keywords Gravitational lensing: weak, Methods: data analysis, Methods: statistical, Techniques: image processing, Cosmology: observations, Large-scale structure of Universe.


Published Journal Article (1.4 Mb)

Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2010 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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