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XMM-Newton Science Analysis System


ewavelet (ewavelet-3.8) [xmmsas_20060628_1801-7.0.0]

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Avoiding spurious detections near edges in the image

The algorithm used to prevent the detection of spurious sources near sharp gradients in the exposure (e.g. chip edges) has been changed as of version ewavelet v3.3 .

The background map is convolved with the current wavelet filter. This convolved image should show similar features as the convolved input image, if no real sources were present. We only retain sources whose value of $C_{max}$ exceeds the corresponding pixel value in the convolved background map by at least a factor of edgethreshold.