Spurious Shear in Weak Lensing with LSST
  The complete 10-year survey from the Large Synoptic Survey Telescope (LSST)
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 algorithm-independent, \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 source of the errors 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. With the large
multi-epoch dataset that will be acquired by LSST, the stochastic errors
average out, bringing the final spurious shear correlation function to a level
very close to the statistical errors. Our results imply that the cosmological
constraints from LSST will not be severely limited by these
algorithm-independent, additive systematic effects.
