Precision simulation of ground-based lensing data using observations
  from space
  Current and upcoming wide-field, ground-based, broad-band imaging surveys
promise to address a wide range of outstanding problems in galaxy formation and
cosmology. Several such uses of ground-based data, especially weak
gravitational lensing, require highly precise measurements of galaxy image
statistics with careful correction for the effects of the point-spread function
(PSF). In this paper, we introduce the SHERA (SHEar Reconvolution Analysis)
software to simulate ground-based imaging data with realistic galaxy
morphologies and observing conditions, starting from space-based data (from
COSMOS, the Cosmological Evolution Survey) and accounting for the effects of
the space-based PSF. This code simulates ground-based data, optionally with a
weak lensing shear applied, in a model-independent way using a general Fourier
space formalism. The utility of this pipeline is that it allows for a precise,
realistic assessment of systematic errors due to the method of data processing,
for example in extracting weak lensing galaxy shape measurements or galaxy
radial profiles, given user-supplied observational conditions and real galaxy
morphologies. Moreover, the simulations allow for the empirical test of error
estimates and determination of parameter degeneracies, via generation of many
noise maps. The public release of this software, along with a large sample of
cleaned COSMOS galaxy images (corrected for charge transfer inefficiency),
should enable upcoming ground-based imaging surveys to achieve their potential
in the areas of precision weak lensing analysis, galaxy profile measurement,
and other applications involving detailed image analysis.
