Shear Systematics in LSST Simulated Images

The Large Synoptic Survey Telescope (LSST) is a large-aperture, wide-field, ground-based telescope designed to provide a complete survey of 20,000 square degrees of sky in six optical bands every few nights. Over ten years of operation, it will measure the magnitudes, colors, and shapes of several billion galaxies. As such, LSST will probe cosmic shear down to levels far beyond those accessible with current surveys. The unprecedented statistical power of LSST will impose new requirements on the control of weak lensing systematics. Various noise sources become important in this context, associated with counting statistics, atmospheric effects, and wavefront errors introduced by the telescope and camera systems.

We are studying these various noise components and their impact on shear measurements using simulated LSST images produced by a prototype high fidelity photon-by-photon Monte Carlo code. The code includes the most significant physical effects associated with photon propagation through the atmosphere, reflection off of the three mirror surfaces of the telescope, and propagation through the elements of the camera and on into the detector. We report on preliminary results from this program, including plots of residual shear error correlation functions due to errors in the object shape estimation for realistic LSST operating conditions.