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XMM­Newton Science Analysis System Page: 1
epfast
Richard Saxton (XMM SOC)
April 24, 2008
Abstract
Applies a rate­dependent CTI correction to PN fast mode events.
1 Status
version (from VERSION ): 0.3
2 Change history
Revision no. Date Author Comments
0.1 2008­04­24 RDS initial version ­ submitted for approval
3 Instruments/Modes
Instrument Mode
EPIC PN TIMING,BURST
4 Use
pipeline processing no
interactive analysis yes
5 Usage and Examples
Here is a typical example of running epfast on an event file:
epfast evfile=NGC4151filtered.ds tbinwidth=100
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6 Description
6.1 Introduction
The epfast task is designed to correct for a CTI e#ect which has been seen in EPIC­pn fast mode (timing,
burst mode) data. Firstly, it finds the count rate of electrons which have been recorded at a given time
in a given column of the CCD. It then applies a formula to this rate to calculate a correction value for
the CTI.
Eout = Ein/(a0 # rate a1 + a2) (1)
where Ein is the initial PI value of the event, Eout is the final PI value and rate is the number of electrons
per second observed in a particular column at a given time. The coe#cients, a0, a1 and a2 have been
calibrated using in­orbit data and are di#erent for Timing and Burst mode. The number of electrons is
derived from the total PI charge deposited on the column at that time.
7 Parameters
This section documents the parameters recognized by this task (if any).
Parameter Mand Type Default Constraints
evfile yes string Name of existing event
file
a specifier which must point to a table of events in a data set.
timebinwidth no real 10.0 Time bin width
the width of time bins to use when calculating the correction factors. It is in units of seconds.
pimin no int 100 Minimum PI channel
to use
the minimum PI channel to use from the data when calculating the count rate. This may be changed to
avoid low­energy noise.
pimax no int 12000 Maximum PI channel
to use
the maximum PI channel to use from the data when calculating the count rate. This may be changed to
avoid high­energy noise.
withrandomisation no boolean true Whether to use ran­
domisation
Because of the quantised nature of the PI channels it is possible when multiplying by a constant to get
an output PI channel which is not filled by any of the input channels. To avoid this the PI channels are
internally set to be +/­ 0.5 of their initial value before applying the constant. Set withrandomisation to
false to avoid this behaviour.
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8 Errors
This section documents warnings and errors generated by this task (if any). Note that warnings and
errors can also be generated in the SAS infrastructure libraries, in which case they would not be docu­
mented here. Refer to the index of all errors and warnings available in the HTML version of the SAS
documentation.
ThisIsNotEPN (error)
No EPIC­pn data set given
ThisIsNotFAST (error)
The observaiton mode is neither FAST TIMING nor FAST BURST
9 Input Files
1. a data set with a table containing events to be processed.
10 Output Files
1. the input data set with modified PI channel column
11 Algorithm
12 Future developments
13 Developer's notes
13.1 CAL usage
Uses the RATE DEPENDENT CTI table from the CCF element EPN CTI .
14 Comments
References
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