An unbiased estimator for the ellipticity from image moments

Nicolas Tessore

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    Abstract

    An unbiased estimator for the ellipticity of an object in a noisy image is given in terms of the image moments. Three assumptions are made: i) the pixel noise is normally distributed, although with arbitrary covariance matrix, ii) the image moments are taken about a fixed centre, and iii) the point-spread function is known. The relevant combinations of image moments are then jointly normal and their covariance matrix can be computed. A particular estimator for the ratio of the means of jointly normal variates is constructed and used to provide the unbiased estimator for the ellipticity. Furthermore, an unbiased estimate of the covariance of the new estimator is also given.
    Original languageEnglish
    Pages (from-to)L57-L60
    JournalRoyal Astronomical Society. Monthly Notices. Letters
    Volume471
    Issue number1
    Early online date14 Jul 2017
    DOIs
    Publication statusPublished - 11 Oct 2017

    Keywords

    • astro-ph.CO
    • math.ST
    • stat.TH

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