XMM-Newton Science Analysis System
ewavelet (ewavelet-3.12) [xmmsas_20211130_0941-20.0.0]
The wavelet detection involves the following steps:
- Read the input image and the exposure map.
- Generate the countrate image from the input image and exposure map.
- Generate the initial background map by scaling the exposure map in such
a way that the background map contains as many “counts” as the input image.
- Do the following for several wavelet scales:
|1|| generate a background map for this particular scale|
|2|| convolve image with the MH wavelet function|
|3|| find local maxima in the convolved image|
|4|| Check if the local maximum is significant|
|5|| If the maximum is significant, add the point to the source list
and calculate the number of counts from the wavelet
correlation value ()
- Determine if some sources were detected at several wavelets scales.
If so, choose the wavelet scale with the highest local correlation value.
- Use the detections of the same source at several wavelet scale to
get some information on the source properties.
- Make a new iteration or generate the final source list.
Block diagram of the wavelet source detection algorithm.
XMM-Newton SOC -- 2021-11-30