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2002ApJS..138..185F - Astrophys. J., Suppl. Ser., 138, 185-218 (2002/January-0)
A wavelet-based algorithm for the spatial analysis of Poisson data.
FREEMAN P.E., KASHYAP V., ROSNER R. and LAMB D.Q.
Abstract (from CDS):
In this paper, we describe the mission-independent, wavelet-based source detection algorithm "WAVDETECT'', part of the freely available Chandra Interactive Analysis of Observations (CIAO) software package. Our algorithm uses the Marr, or "Mexican Hat'' wavelet function, but may be adapted for use with other wavelet functions. Aspects of our algorithm include: (1) the computation of local, exposure-corrected normalized (i.e., flat-fielded) background maps; (2) the correction for exposure variations within the field of view (due to, e.g., telescope support ribs or the edge of the field); (3) its applicability within the low-counts regime, as it does not require a minimum number of background counts per pixel for the accurate computation of source detection thresholds; (4) the generation of a source list in a manner that does not depend upon a detailed knowledge of the point spread function (PSF) shape; and (5) error analysis. These features make our algorithm considerably more general than previous methods developed for the analysis of X-ray image data, especially in the low count regime. We demonstrate the robustness of WAVDETECT by applying it to an image from an idealized detector with a spatially invariant Gaussian PSF and an exposure map similar to that of the Einstein IPC; to Pleiades Cluster data collected by the ROSAT PSPC; and to simulated Chandra ACIS-I image of the Lockman Hole region.
Abstract Copyright: ∼
Journal keyword(s): Methods: Data Analysis - Techniques: Image Processing - X-Rays: General
Simbad objects: 4
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