The third gravitational lensing accuracy testing (GREAT3) challenge handbook

Rachel Mandelbaum, Barnaby Rowe, James Bosch, Chihway Chang, Frederic Courbin, Mandeep Gill, Mike Jarvis, Arun Kannawadi, Tomasz Kacprzak, Claire Lackner, Alexie Leauthaud, Hironao Miyatake, Reiko Nakajima, Jason Rhodes, Melanie Simet, Joe Zuntz, Bob Armstrong, Sarah Bridle, Jean Coupon, Jörg P. DietrichMarc Gentile, Catherine Heymans, Alden S. Jurling, Stephen M. Kent, David Kirkby, Daniel Margala, Richard Massey, Peter Melchior, John Peterson, Aaron Roodman, Tim Schrabback

Research output: Contribution to journalArticlepeer-review

136 Scopus citations


The GRavitational lEnsing Accuracy Testing 3 (GREAT3) challenge is the third in a series of image analysis challenges, with a goal of testing and facilitating the development of methods for analyzing astronomical images that will be used to measure weak gravitational lensing. This measurement requires extremely precise estimation of very small galaxy shape distortions, in the presence of far larger intrinsic galaxy shapes and distortions due to the blurring kernel caused by the atmosphere, telescope optics, and instrumental effects. The GREAT3 challenge is posed to the astronomy, machine learning, and statistics communities, and includes tests of three specific effects that are of immediate relevance to upcoming weak lensing surveys, two of which have never been tested in a community challenge before. These effects include many novel aspects including realistically complex galaxy models based on high-resolution imaging from space; a spatially varying, physically motivated blurring kernel; and a combination of multiple different exposures. To facilitate entry by people new to the field, and for use as a diagnostic tool, the simulation software for the challenge is publicly available, though the exact parameters used for the challenge are blinded. Sample scripts to analyze the challenge data using existing methods will also be provided. See and more information.

Original languageEnglish (US)
Article number5
JournalAstrophysical Journal, Supplement Series
Issue number1
StatePublished - May 2014
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • gravitational lensing: weak
  • methods: data analysis
  • methods: statistical
  • techniques: image processing


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