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XMM-Newton Science Analysis System


omphotom (omphotom-0.6.6) [xmmsas_20070708_1801-7.1.0]

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Description

This program is designed to allow a user to recompute the photometry of one or more sources in an OM product source-list file, in one of several different ways, using specified parameters. Whilst omsource can be used to recompute the photometry from a given source-list file, omphotom will be quicker if a list of sources from various source-list files need reprocessing. Omphotom also allows the photometry to be re-computed using several different methods.

The program allows OM FAST data to be reprocessed, and in order to estimate the background more reliably the appropriate IMAGING image can be used to determine the background.

The photometry can be computed by least-squares fitting of the point-spread function to one or more sources. This can significantly increase the accuracy of the photometry in the case of sources with one or more close neighbours. Currently, the photometry carried out by omdetect is done by aperture photometry, and therefore it may be desireable to use omphotom to re-compute the photometry of some sources. For the case of FAST mode data, omlcbuild uses the PSF to compute the photometry and obtains the background from pixels surrounding the source from. Since it does not take account of close neighbours, for such cases omphotom may also prove useful.