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XMM­Newton CCF Release Note
XMM­CCF­REL­221
Update of EPIC MOS2 CTI epoch revs. 446­533
Martin Stuhlinger, Darren Baskill
October 31, 2006
1 CCF components
Name of CCF VALDATE EVALDATE List of Blocks CAL XSCS
(start of val. period) (end of validity period) changed VERSION flag
EMOS2 CTI 0030 2002­05­16T05:00:01 2002­11­07T05:00:00 CTI EXTENDED NO
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2 Changes
The new MOS2 CTI CCF issue 30 has been created with updated CTI parameters for all MOS2
CCDs. This new CCF replaces the previous MOS2 CTI CCF issue 24 (see XMM­CCF­REL­206)
and covers the same time period 2002­05­16 to 2002­11­07 (revs. 446­533).
Using CCF EMOS2 CTI 0024.CCF it was found that low energy images of MOS2 CCD4 were
incomplete; high RAWX columns were not present in the images. There was also a RAWX/PI
dependence --- as the upper PI selection threshold was lowered the area of blank CCD increased.
The e#ect is presented in Fig. 1. The cause was found in the parameter setting of the MOS2 CCD4
serial CTI
CT IY (E) = 601.97 # E -1.83
For this epoch the serial CTI is not time dependent, therefore the parameter describing the time
dependency is set to zero. This parameter set returned very high CTI values at low energies,
therefore after a certain amount of shifts no event could pass the energy threshold any more. As
low RAWX columns are shifted less than columns with high RAWX values, the low energy images
showed only the low RAWX columns and the high RAWX columns were missing.
For this particular epoch alone, and for MOS2 CCD4 only, the serial CTI loss for the Mn­
K# calibration line (at #6 keV) appeared to reduce to almost zero, whilst the serial CTI at Al­K
(#1.5 keV) remained nominal. The new CTI calculations prevent the serial CTI from having such
a negative energy dependence.
Beside of this low energy cut­o#, the interaction of CTI and ADUCONV parameters took care
that the energy reconstruction of the events were correct. The energy positions of the internal
calibration lines were accurate by better than 5 eV at Al­K and Mn­K.
Figure 1: MOS2 CCD4 RAWX/RAWY low energy images using the incorrect MOS2 CCD4 serial
CTI parameters. Left to right: PI < 300 eV; PI < 400 eV; PI < 500 eV; PI < 600 eV
3 Scientific Impact of this Update
The use of this CCF will enable correct low energy analyses on MOS2 CCD4 for the corresponding
epoch. The new CTI CCF is released together with a new ADUCONV CCFs (issue 42, see XMM­
CCF­REL­222), since the new cti with old gains, and old cti with new gains may give unexpected
results!

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4 Estimated Scientific Quality
This issue assures that the MOS energy scale remains within 5 eV at 2 keV, and 10 eV at 6 keV for
most sources (not too bright), for all observations (see a more detailed discussion in XMM­CCF­
REL­124).
5 Test procedures & results
The new CTI CCFs have been tested with the SASv7.0. No RAWX/PI dependence in low energy
images was found any more.
6 Expected Updates
So far a common CTI model has been used for all columns of a single MOS CCD. In reality, the
CTI di#ers slightly between di#erent columns. Some MOS columns show significantly di#erent CTI
behaviour within di#erent sections of the column.
The calibration team is currently working on a column dependent CTI which can take into
account di#erent CTI behaviour of the individual columns as well as di#erent behaviour of sections
within a single column.