C. Chang, S. M. Kahn, J. G. Jernigan, J. R. Peterson, Y. AlSayyad, Z. Ahmad, J. Bankert, D. Bard, A. Connolly, R. R. Gibson, K. Gilmore, E. Grace, M. Hannel, M. A. Hodge, M. J. Jee, L. Jones, S. Krughoff, S. Lorenz, P. J. Marshall, S. Marshall, A. Meert, S. Nagarajan, E. Peng, A. P. Rasmussen, M. Shmakova, N. Sylvestre, N. Todd, M. Young
The Large Synoptic Survey Telescope (LSST) is one of the most powerful ground-based weak lensing survey telescopes in the upcoming decade. The complete 10-year survey will image $\sim$ 20,000 square degrees of sky in six filter bands every few nights, bringing the final survey depth to $r\sim27.5$, with over 4 billion well measured galaxies. To take full advantage of this unprecedented statistical power, the systematic errors associated with weak lensing measurements need to be controlled to a level similar to the statistical errors. This work is the first attempt to quantitatively estimate the absolute level and statistical properties of the systematic errors on weak lensing shear measurements due to the most important physical effects in the LSST system via high fidelity ray-tracing simulations. We identify and isolate the different sources of \textit{additive} systematic errors on shear measurements for LSST and predict their impact on the final cosmic shear measurements using conventional weak lensing analysis techniques. We find that the main additive systematic error on the shear measurements comes from an inability to adequately characterise the atmospheric point spread function (PSF) due to its high frequency spatial variation on angular scales smaller than $\sim10'$ in the single short exposures, which propagates into a spurious shear correlation function at the $10^{-4}$--$10^{-3}$ level on these scales. Nevertheless, with the large multi-epoch dataset that will be acquired by LSST, the stochastic errors from the instrument and the atmosphere average out, bringing the final systematic errors to a level very close to the statistical errors. Although our results imply that the cosmological constraints from LSST will not be severely limited by these systematic effects, they also raise potential problems with the use of traditional weak lensing algorithms.
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http://arxiv.org/abs/1206.1378
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