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XMM­Newton CCF Release Note
XMM­CCF­REL­213
Evolution of the RGS CTI
A.M.T. Pollock
June 29, 2006
1 CCF components
Name of CCF VALDATE List of Blocks changed XSCS flag
RGS1 CTI 0008 2004­05­09T02:00:00 XCTI NO
CTIY1 NO
CTIY2 NO
CTIY3 NO
CTIY4 NO
CTIY5 NO
CTIY6 NO
CTIY7 NO
CTIY8 NO
CTIY9 NO
RGS2 CTI 0009 2004­05­09T02:00:00 XCTI NO
CTIY1 NO
CTIY2 NO
CTIY3 NO
CTIY4 NO
CTIY5 NO
CTIY6 NO
CTIY7 NO
CTIY8 NO
CTIY9 NO
2 Changes
CCDs in space are subject to particle radiation damage that causes charge transfer characteristics
to change. It is part of the RGS routine calibration plan periodically to do observations of suitably
bright targets towards the upper and lower edges of the CCDs in the cross­dispersion direction in
order to assess the evolution of the CTI. Two such o#set observations of Mkn421 were done in
1

XMM­Newton CCF Release XMM­CCF­REL­213 Page: 2
Figure 1: New XCTI values in green compared with their previous values for RGS1 in red on the
right and RGS2 in blue on the left. For each CCD, there are separate values for each node.
rev 1083. These gave rise to the revisions released here. The XCTI values are shown in Fig. 1 in
comparison with their previous values.
3 Scientific Impact of this Update
TBD.
4 Estimated Scientific Quality
More robust event PI values leading to more reliable selection regions.
5 Test procedures & results
This CCF is part of the overall calibration e#ort whose final results are described in the new RGS
e#ective area model described in XMM­SOC­CAL­SRN­0216. Nonetheless, internal consistency of
the CTI values has been confirmed by ensuring the consistency of the PI distributions of the Mkn421
observations performed on­axis and with postive and negative cross­dispersion o#sets in revs 1083
and 1084.
6 Expected Updates
It is expected that similar o#set observations of Mkn421 will be performed every two years.