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XMM­Newton CCF Release Note
XMM­CCF­REL­201
Further refinement of EPIC­pn frame times and clock sequences
M. Kirsch
November 8, 2006
1 CCF components
Name of CCF VALDATE List of Blocks
changed
XSCS flag
EPN TIMECORR 0011 1998­01­01T00:00:00 FRAMETIME
FRAME TIME
NO
EPN TIMECORR 0012 1998­01­01T00:00:00 2000­02­09T11:00:00 FRAMETIM
EFRAME TIME
NO
EPN TIMECORR 0013 2000­02­09T22:00:00 2000­03­01T00:00:00 FRAMETIME
FRAME TIME
NO
EPN TIMECORR 0014 2000­03­04T12:00:00 2000­03­08T15:00:00 FRAMETIME
FRAME TIME
NO
EPN TIMECORR 0015 2000­03­11T00:00:00 2000­03­18T00:00:00 FRAMETIME
FRAME TIME
NO
EPN TIMECORR 0011 1998­01­01T00:00:00 TIMECOR
FRAME TIME
NO
EPN TIMECORR 0012 1998­01­01T00:00:00 2000­02­09T11:00:00 TIMECOR
FRAME TIME
NO
EPN TIMECORR 0013 2000­02­09T22:00:00 2000­03­01T00:00:00 TIMECOR
FRAME TIME
NO
EPN TIMECORR 0014 2000­03­04T12:00:00 2000­03­08T15:00:00 TIMECOR
FRAME TIME
NO
EPN TIMECORR 0015 2000­03­11T00:00:00 2000­03­18T00:00:00 TIMECOR
FRAME TIME
NO
2 Changes
Frame times and values to determine the correct photon arrival times have been calibrated using in
orbit data.
1

XMM­Newton CCF Release XMM­CCF­REL­201 Page: 2
3 Scientific Impact of this Update
The new CCFs will not significantly e#ect the timing accuracy as such, but will help to identify still
present time jumps in the data more accurately. Before, the time jump detection algorithm of the
OAL using the not perfect timing parameters needed to be operated with a higher margin in order
to avoid drift e#ects created by the non fully correct frame times, especially for long observations
and counting mode intervals.
4 Estimated Scientific Quality
The changes in the frame times are of the order of less then 20 clocks (20*40 ns = 800 ns = 0.8
micro sec). This is not a#ecting at all the timing properties of the EPIC­pn camera as it is shown
in section 6.
5 Expected Updates
With the new CCFs the OAL time jump detection algorithm will be refined.
6 Test procedures & results
The the new EPN TIMECORR 00011 ­EPN TIMECORR 00015 CCFs have been tested on all
available archive data comparing the di#erences of 2 consecutive events. This di#erences should be
near to a multiple of the frame time and be constant with the observation time.
Figure 1 shows the evolving di#erences between consecutive events, plotting the slope of a linear
fit to the time di#erences of consecutive events modulo the frame time. In the upper panel with the
old and in the lower panel with the new frame times.
The CCFs have been verified using all calibration Crab data from the relative timing monitoring.
As expected the timing results are not a#ected at all by the refined frame times.

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200 400 600 800 1000 1200
revolution
­5.10 ­5
0
5.10 ­5
slope
of
timediffs
[frametimes]
FF
EFF
SW
LW
T
B
200 400 600 800 1000 1200
revolution
­5.10 ­5
0
5.10 ­5
slope
of
timediffs
[frametimes]
FF
EFF
SW
LW
T
B
Figure 1: Evolving di#erences between consecutive events, plotting the slope of a linear fit to the
time di#erences of consecutive events modulo the frame time. Upper with old frame times, lower
with refined ones.