I get strange edge-like features in my pn spectrum. Is therefore
something I need to know?
A bug has been found in
arfgen, which affects pn spectra extracted from
annuli. The energy interpolation in the encircled energy correction
employed by
arfgen is incorrect. This can lead to a
saw-tooth response
between 2 and 7 keV, and then again between 7 and 12 keV.
This may mimic an absorption edge
in the spectral fitting.
This has been fixed in SAS 5.4; in the meantime the problem can be
solved by specifying the extra parameter eegridfactor on the
arfgen
command line, e.g.:
arfgen [your_parameters] eegridfactor=10
This bug does not noticeably affect MOS spectra, nor
pn spectra extracted from circular regions.
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Updated on:
November 18, 2006