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

By Sarah Bridle, S. Balan, Matthias Bethge, M. Gentile, Stefan Harmeling, Catherine Heymans, Michael Hirsch, Reshad Hosseini, Michael J. Jarvis, Donnacha Kirk and 24 more. 2009

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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.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/9d9128a6ddfd6c5080e7e41f4166b7ab7a6db111

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Citations in the corpus

Dark Energy Survey Year 1 results: weak lensing shape catalogues (2017, background): “…such exercises, most notably the Shear Testing Programme and GRavitational lEnsing Accuracy Testing (GREAT) challenges (Heymans et al. 2006; Massey et al. 2007; Bridle et al. 2010; Kitching et al. 2012; Mandelbaum et al. 2015), which have illuminated many of the issues that the field must solve.”
Galaxy Alignments: Observations and Impact on Cosmology (2015, methodology): “This is why image simulations are used to not only compare the performance of algorithms (e.g. Heymans et al. 2006; Bridle et al. 2010; Kitching et al. 2012; Mandelbaum et al. 2015), but also to calibrate algorithms (e.”
GalSim: The modular galaxy image simulation toolkit (2014, methodology): “Simulations of weak lensing survey data in the GREAT08 (GRavitational lEnsing Accuracy Testing 2008) challenge (Bridle et al., 2010) clearly showed the impact of noise in a blind comparison of shear estimation methods.”
The Canadian Cluster Comparison Project: detailed study of systematics and updated weak lensing masses (2015, background): “A strong dependence of the bias on the SNR was already observed in Bridle et al. (2010) and Kitching et al. (2012).”
Galaxy Alignments: An Overview (2015, background): “This in turn renders the estimation of gravitational shear from noisy, small and pixelated galaxy images a challenge, which has spawned large community effort to develop more powerful algorithms (Heymans et al. 2006b; Massey et al. 2007; Bridle et al. 2010; Kitching et al. 2012; Mandelbaum et al. 20”
Observational probes of cosmic acceleration (2012, methodology): “Equally important, these methods were tested in public challenges on simulated data (Heymans et al., 2006; Massey et al., 2007b; Bridle et al., 2010).”
Origins of weak lensing systematics, and requirements on future instrumentation (or knowledge of instrumentation) (2012, methodology): “Similar behaviour is suggested in GREAT08 (Bridle et al. 2010, figure C3) and is explicitly fitted in GREAT10 (Kitching et al. 2012a, appendix B5) as m ≈ m0 + αR2PSF 〈R2gal〉〈R2PSF〉 R2PSF 〈R2gal〉 (79) where 〈R2PSF〉 = 3.42 pixels2, 〈R2gal〉 ≈ 3.552 pixels2 (averaging the contribution of the bulges…”
Gravitational lensing (2010, unknown): “the STEP programme [186, 311] and the GREAT08 challenge [56].”
CFHTLenS: the Canada–France–Hawaii Telescope Lensing Survey – imaging data and catalogue products (2012, methodology): “…and deepwide survey observations have been paralleled by significant community efforts in algorithm development in order to overcome the challenges of this non-trivial observation (Heymans et al. 2006a; Massey et al. 2007a; Bridle et al. 2010; Hildebrandt et al. 2010; Kitching et al. 2012a,b).”
The WiggleZ Dark Energy Survey: Direct constraints on blue galaxy intrinsic alignments at intermediate redshifts (2009, background): “…to solving the technical problems in measuring the weak lensing signal, primarily related to unbiased shear estimation (Heymans et al. 2006b; Massey et al. 2007a; Bridle et al. 2009) and to photometric redshifts (Bernstein & Jain 2004; Ishak & Hirata 2005; Huterer et al. 2006; Abdalla et al. 2008).”
The DES Science Verification weak lensing shear catalogues (2015, background): “A number of blind challenges of shear measurements have been carried out to assess progress in a uniform way across the international shear measurement community: the Shear TEsting Programme (STEP Heymans et al. 2006; Massey et al. 2007) and the GRavitational lEnsing Accuracy Testing (GREAT) Challen”
Constraints on intrinsic alignment contamination of weak lensing surveys using the MegaZ-LRG sample (2010, background): “…data for high-precision measurements have concentrated on technical issues, in particular the unbiased extraction of shapes from galaxy images (e.g. Bridle et al. 2010; Bernstein 2010; Cypriano et al. 2010; Voigt & Bridle 2010) and the estimation of galaxy redshifts from multi-colour photometry…”
Bayesian galaxy shape measurement for weak lensing surveys – III. Application to the Canada–France–Hawaii Telescope Lensing Survey (2012, methodology): “The image simulations were produced using a modified version of the GREAT challenges image simulation software package detailed in appendix A.3 of Bridle et al. (2010).”
Cosmological parameter constraints from galaxy-galaxy lensing and galaxy clustering with the SDSS DR7 (2012, background): “…as for the + component, and 27 This result is expected, because systematic errors in determination of the shear generically depend on both the S/N and apparent size of the source compared to the PSF; e.g., Bridle et al. (2010) and Kitching et al. (2012). c© 0000 RAS, MNRAS 000, 000–000 Figure B3.”
The first-year shear catalog of the Subaru Hyper Suprime-Cam Subaru Strategic Program Survey (2017, background): “This evolution has been demonstrated through a series of community challenges (Heymans et al. 2006; Massey et al. 2007b; Bridle et al. 2009, 2010; Kitching et al. 2010, 2012; Mandelbaum et al. 2014, 2015).”