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Abstract: Anisotropy in the point spread function PSF contributes a systematic errorto weak lensing measurements. In this study we use a ray tracer thatincorporates all the optical elements of the SNAP telescope to estimate thiseffect. Misalignments in the optics generates PSF anisotropy, which wecharacterize by its ellipticity. The effect of three time varying effects:thermal drift, guider jitter, and structural vibration on the PSF are estimatedfor expected parameters of the SNAP telescope. Multiple realizations of athousand square degree mock survey are then generated to include the systematicerror pattern induced by these effects. We quantify their contribution to thepower spectrum of the lensing shear. We find that the dominant effect comesfrom the thermal drift, which peaks at angular wavenumbers l ~ 10^3, but itsamplitude is over one order of magnitude smaller than the size of the expectedstatistical error. While there are significant uncertainties in our modeling,our study indicates that time-varying PSFs will contribute at a smaller levelthan statistical errors in SNAP-s weak lensing measurements.

Autor: H. F. Stabenau, B. Jain, G. Bernstein, M. Lampton

Fuente: https://arxiv.org/

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