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Proceedings Paper

The MATPHOT algorithm for digital point spread function CCD stellar photometry
Author(s): Kenneth J. Mighell
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Paper Abstract

The MATPHOT algorithm for digital Point Spread Function (PSF) CCD stellar photometry is described. A theoretical photometric and astrometric performance model is presented for PSF-fitting stellar photometry. MATPHOT uses a digital representation of the sampled PSF consisting of a numerical table (e.g., a matrix or a FITS image) instead of an analytical function. MATPHOT achieves accurate stellar photometry with under-sampled CCD observations with super-sampled PSFs. MATPHOT currently locates a PSF within the observational model using a 21-pixel-wide damped sinc interpolation function. Position partial derivatives of the observational model are determined using numerical differentiation techniques. Results of MATPHOT-based design studies of the optical performance of the Next Generation Space Telescope are presented; observations of bright stars analyzed with the MATPHOT algorithm can yield millimag photometric errors with millipixel relative astrometric errors -- or better -- if observed with a perfect detector. Plans for the future development of a parallel-processing version of the MATPHOT algorithm using Beowulf clusters are described. All of the C source code and documentation for MATPHOT is freely available as part of the MXTOOLS package for IRAF ( This work is supported by a grant from NASA's Office of Space Science.

Paper Details

Date Published: 19 December 2002
PDF: 10 pages
Proc. SPIE 4847, Astronomical Data Analysis II, (19 December 2002); doi: 10.1117/12.460444
Show Author Affiliations
Kenneth J. Mighell, National Optical Astronomy Observatory (United States)

Published in SPIE Proceedings Vol. 4847:
Astronomical Data Analysis II
Jean-Luc Starck; Fionn D. Murtagh, Editor(s)

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