Abstract: |
The measurement of weak lensing shear is regarded as a key method of observational cosmology. However, the measurement is extremely difficult, requiring us to measure to high accuracy the shapes of faint galaxies in the presence of photon noise, convolution with the telescope PSF, telescope distortion and finite image sampling. For the recently published CFHTLenS survey, we developed a (mostly) bayesian method for making this measurement. I shall describe the basic principles of the bayesian shear measurement method and how it was implemented for CFHTLenS, and also discuss some of the key remaining issues that must be resolved if we are to obtain more accurate results from upcoming surveys, which are larger than CFHTLenS and require even better control of systematic errors. I shall also summarise briefly the key science results of CFHTLenS. |