described at URL: https://chandra.si.edu/photo/2001/0004/more.html URL: https://chandra.si.edu/photo/2001/0004/0004_xray_zoom.tif determination method...
described at URL: https://chandra.si.edu/photo/2001/0004/more.html URL: https://chandra.si.edu/photo/2001/0004/0004_xray_zoom.jpg determination method...
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