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The Shear Testing Programme - I. Weak lensing analysis of simulated ground-based observations

Catherine Heymans 1 Ludovic van Waerbeke 2 David Bacon 3 Joel Bergé 4 Gary Bernstein 5 Emmanuel Bertin 6 Sarah Bridle 7 Michael L. Brown 3 Douglas I. Clowe 8 Håkon Dahle 9 Thomas Erben 10 Meghan Gray 11 Marco Hetterscheidt 10 Henk Hoekstra 12 Patrick Hudelot 13 Mike Jarvis 5 Konrad Kuijken 14 Vera Margoniner 15 Richard Massey 16 Yannick Mellier 6, 17 Reiko Nakajima 5 Alexandre Réfrégier 4 Jason D. Rhodes 18 Tim Schrabback 10 David Wittman 15 
Abstract : The Shear Testing Programme (STEP) is a collaborative project to improve the accuracy and reliability of all weak lensing measurements in preparation for the next generation of wide-field surveys. In this first STEP paper, we present the results of a blind analysis of simulated ground-based observations of relatively simple galaxy morphologies. The most successful methods are shown to achieve percent level accuracy. From the cosmic shear pipelines that have been used to constrain cosmology, we find weak lensing shear measured to an accuracy that is within the statistical errors of current weak lensing analyses, with shear measurements accurate to better than 7 per cent. The dominant source of measurement error is shown to arise from calibration uncertainties where the measured shear is over or underestimated by a constant multiplicative factor. This is of concern as calibration errors cannot be detected through standard diagnostic tests. The measured calibration errors appear to result from stellar contamination, false object detection, the shear measurement method itself, selection bias and/or the use of biased weights. Additive systematics (false detections of shear) resulting from residual point-spread function anisotropy are, in most cases, reduced to below an equivalent shear of 0.001, an order of magnitude below cosmic shear distortions on the scales probed by current surveys.
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Catherine Heymans, Ludovic van Waerbeke, David Bacon, Joel Bergé, Gary Bernstein, et al.. The Shear Testing Programme - I. Weak lensing analysis of simulated ground-based observations. Monthly Notices of the Royal Astronomical Society, 2006, 368, pp.1323-1339. ⟨10.1111/j.1365-2966.2006.10198.x⟩. ⟨hal-03786091⟩



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