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Paper: Star Finding and PSF Determination using Image Restoration
Volume: 77, Astronomical Data Analysis Software and Systems IV
Page: 293
Authors: Hook, R. N.; Lucy, L. B.
Abstract: Crowded-field stellar photometry consists of three main phases: locating the point sources, determining the point spread function (PSF) and measuring the point source brightnesses. In earlier work (Lucy 1994; Hook & Lucy 1994) we have described a two-channel restoration method which provides photometric fidelity and addresses the last of these items in a restoration context. Here we describe two further enhancements. First, an experimental method for locating stellar images by enhancing the sharp cores of stars using a multi-channel entropy minimization technique is described. In addition an extended version of the two-channel method is given which allows PSFs to be extracted from designated point-sources in images during restoration. A default PSF may be used to regularize the result. A simple but accurate model for the form of ground-based PSFs (Saglia et al. 1993) has been implemented and seems a suitable choice of default PSF for ground-based images. Examples using a typical ground-based CCD image of a star cluster are given. These methods are available in preliminary implementations running within both the IRAF and MIDAS data analysis packages.
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