## Improving the accuracy of mass reconstructions from weak lensing: local shear measurements
Different options can be used in order to measure the shear from observations in the context of weak lensing. Here we introduce new methods where the isotropy assumption for the distribution of the source galaxies is implemented directly on the observed quadrupole moments. A quantitative analysis of the error associated with the finite number of source galaxies and with their ellipticity distribution is provided, applicable even when the shear is not weak. Monte Carlo simulations based on a realistic sample of source galaxies show that our procedure generally leads to errors smaller than those associated with the standard method of Kaiser and Squires (1993).
## Contents- 1. Introduction
- 2. The isotropy hypothesis and the "standard" method
- 3. Alternative methods based on the observed average quadrupole
- 4. Monte Carlo simulations
- 4.1. Source galaxies
- 4.2. Simulations and results
- 5. Conclusions
- Acknowledgements
- Appendix A: the expected covariance matrix for a sharp ellipticity distribution
- Appendix B: basic structure of the simulation algorithm
- References
© European Southern Observatory (ESO) 1998 Online publication: January 27, 1998 |