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XMM­Newton CCF Release Note
XMM­CCF­REL­228
pn modified Timing mode response matrix
M. Kirsch
July 10, 2007
1 Purpose
Using the EPIC­pn CCD camera in Timing mode, in which data are read out continuously, telemetry
constraints do not allow full use of the capabilities for very bright sources because currently randomly
distributed data gaps are introduced by the on­board data handling electronics. As an alternative a
modification of the Timing mode in which data from soft X­ray events are not transmitted to Earth
is available called ''the modified Timing mode''. The mode has first been used by XMM­Newton for
the following observations of the Galactic Black Hole binary Cygnus X­1 in autumn 2004:
. 0202760201
. 0202760301
. 0202760401
. 0202760501
More details on the modified Timing mode can be found in:
. Bright source x­ray spectroscopy with XMM­Newton: a modified EPIC­pn Timing mode,
Kendziorra et al, SPIE, Volume 5488, pp. 613­622 (2004). (see XMM­SOC­CAL­TN­0073 )
. EPIC­pn observations of Cygnus X­1, Wilms et al., ESA SP­604, January 2006
http://xmm.esac.esa.int/external/xmm science/workshops/x­ray­symposium/172094 jw cygx1.pdf
Currently the SAS can not provide response matrices for the modified Timing mode.
1

XMM­Newton CCF Release XMM­CCF­REL­228 Page: 2
However we provide a canned matrix at the calibration portal in the response matrix section at:
http://xmm.esac.esa.int/external/xmm sw cal/calib/epic files.shtml
This matrix allows to perform spectral analysis of the data of the modified Timing mode. Note
that the matrix includes already an ARF and can only be used for a spectrum that has been
extracted from columns 20­35 and 39­54 in order to assure correct normalization.
2 Changes
Using all available Timing mode data in standard setting simulating a higher lower threshold pattern
fractions have been determined for a lower threshold of 2.8 keV. The response matrix contains also
the ARF in that case.
3 Scientific Impact of this Update
The matrix will allow the general user to spectrally analyze the mentioned observations. In or­
der to perform a correct analysis a spectrum needs to be extracted with the following expression
expression='' FLAG.eq.0 .AND. PI.GE.300 .AND. PI.LE.10000 .AND. (PATTERN.GE.0 .AND.
PATTERN.LE.4) .AND. (RAWX IN [20:35] .OR. RAWX IN [39:54])
The modfied Timing mode gives the possibility to observe (very) bright (up to 1 Crab) sources
without the caveat of entering counting mode. This is especially important regarding time series
analysis and the study of iron line variability, since the mode provides uninterrupted data streams.
4 Estimated Scientific Quality
The observations mentioned in section 1 show gain shifts due to imperfect CTI calibration of the
Timing mode for very high photon rates. This is not been taken into account by the response matrix
provided at the SOC. Currently work is ongoing to model the CTI/Gain for very bright sources for
the Timing and Burst mode. Corrections need to be applied on a column by column basis and should
not be averaged over the whole CCD. The resulting shifts around 6 keV for the above mentioned
observations are around 100­200 eV. A preliminary matrix also taking the special CTI situation for
the above mentioned observations into account is provided by the PI of the observations on request.
Please send an email to joern.wilms@sternwarte.uni­erlangen.de.
5 Test procedures & results
The matrix has been tested on all in section 1 mentioned observations.

XMM­Newton CCF Release XMM­CCF­REL­228 Page: 3
10 0
10 1
normalized
counts
s
-1
keV
-1
-10
0
10
Energy [keV]
c
4 6 9
Vela X-1
10 0
10 1
normalized
counts
s
-1
keV
-1
-10
0
10
Energy [keV]
c
4 6 9
Vela X-1
Figure 1: Upper: Standard Timing mode (purple), versus simulated modified Timing mode (red)
both using the standard response matrix. Lower: same but using the new modified matrix for the
modified Timing mode (red).
6 Expected Updates
This matrix will be completed in the future by other matrices for other lower thresholds and other
extraction regions.