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XMM­Newton CCF Release Note
XMM­CCF­REL­259
Spectra quality­related CCF constituent XMM SPECQUAL
M. Guainazzi & A .Pollock
October 28, 2009
1 CCF components
Name of CCF VALDATE List of Blocks
changed
Change in CAL HB
XMM SPECQUAL 0001 2000­01­01T00:00:00 EMOS1 SPQ YES
XMM SPECQUAL 0001 2000­01­01T00:00:00 EMOS2 SPQ YES
XMM SPECQUAL 0001 2000­01­01T00:00:00 EPN SPQ YES
XMM SPECQUAL 0001 2000­01­01T00:00:00 RGS1 SPQ BETA YES
XMM SPECQUAL 0001 2000­01­01T00:00:00 RGS1 SPQ WAVE YES
XMM SPECQUAL 0001 2000­01­01T00:00:00 RGS2 SPQ BETA YES
XMM SPECQUAL 0001 2000­01­01T00:00:00 RGS2 SPQ WAVE YES
XMM SPECQUAL 0001 2000­01­01T00:00:00 GAINFIT LIMIT YES
2 Changes
The new CCF component XMM SPECQUAL contains two sets extensions:
. extensions $instrument SPQ* specify the ranges (in unbinned PI, dispersion or wavelength
space) for which spectra are nominally calibrated according to the calibration status docu­
ments 1
. extension GAINFIT LIMIT contains the minimum and maximum values of the gain linear func­
tion parameters, which are consistent with the gain calibration systematic uncertainties
1 Available at the XMM­Newton Calibration portal: http://xmm2.esac.esa.int/external/xmm sw cal/calib/index.shtml
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2.1 $instrument SPQ
Each of these extensions is a binary matrix, containing one row per instrument mode. Each row is
constituted by two columns:
. NGROUPS
. SPE FLAG, a series of NGROUPS pairs of integer numbers, corresponding to the range (``[mini­
mum channel maximum channel]'') in unbinned PI channels where the response matrix is not
nominally calibrated
The goal of this extension is to allow the SAS spectral extractors to properly flag uncalibrated
spectral channels.
2.2 GAINFIT LIMIT
In this subsection, we refer to a ``gain shift function'' as a linear operator which shift the energies
on which the response matrix is defined and the e#ective area curve to match. Without loss of
generality, the algorithm is equivalent to the gain function in Xspec Version 12 and later.
This extension contains one row per instrument and mode. For each row, six parameters are
specified:
. the instrument identified (INSTRUMENT ID)
. the mode identifier (MODE ID)
. the minimum and maximum values of the gain shift function, which are consistent with
the systematic uncertainties on the instrumental gain (GSLOP MIN, GSLOP MAX, GOFFS MIN,
GOFFS MAX). The GSLOP M* and GOFFS M* parameters indicate the slope and the intercept of
the linear relation, respectively.
The G* M* parameters shall be used by the SAS redistribution matrix generator to populate
keywords in the header of the redistribution matrix file. These keyword could be used by spectral
analysis packages to restrict the range of gain fit parameters to values, which reflects our cur­
rent knowledge of the systematic uncertainties on the instrumental gain 2 . Response matrices of
instrument/modes, for which the G* M* parameters above are not defined, shall not contain the
corresponding redistribution matrix keywords.
2 At the time this document is written, a possible implementation of how this keywords can be used in Xspec is
under discussion

XMM­Newton CCF Release XMM­CCF­REL­259 Page: 3
3 Scientific impact of this update
These changes are intended to transfer information on the quality of the spectral calibration of the
XMM­Newton X­ray cameras to spectral analysis software in a way fully transparent to the final
user. They introduce only formal changes to the SAS scientific products, and therefore they are not
expected to yield any impact on the scientific quality of the data as such.
4 Estimated scientific quality
See the previous subsection.
5 Test procedure and results
We have verified that the parameters of a spectral fit of Obs.# do not change if spectra with uncal­
ibrated flagged channel are fit using redistribution matrices whose header bears the aforementioned
G* M* keywords ­ Note: this test has not been performed yet, because the SAS package that should
use this new CCF constituent does not exist.
6 Expected Updates
The values of the parameters in these extensions will be changed whenever an improvement of the
relevant calibration requires it.
Acknowledgments
Valuable comments by R. Saxton and S. Sembay contributed to ultimately shape this new CCF
constituent.