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Astron. Astrophys. 330, 791-800 (1998)

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Improving the accuracy of mass reconstructions from weak lensing: local shear measurements

Marco Lombardi and Giuseppe Bertin

Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy

Received 25 April 1997 / Accepted 16 October 1997


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 [FORMULA] smaller than those associated with the standard method of Kaiser and Squires (1993).

Key words: gravitational lensing – dark matter – methods: statistical

Send offprint requests to: M. Lombardi

© European Southern Observatory (ESO) 1998

Online publication: January 27, 1998