XMM-Newton Science Analysis System
arfgen (arfgen-1.104) [xmmsas_20230412_1735-21.0.0]
Out of time event correction
For EPIC-PN, in particular, there is a mode-dependent loss of photons due to
the readout cycle.
This can result in a
6% dead-time effect for full frame mode. This has been taken into account in
the exposure time in the spectrum header for files created with pipeline
versions greater than 20010618 but wasn't catered for in earlier pipeline
runs. arfgen
checks the PPSVERS keyword in the file header
and applies the correction to the output ARF if the pipeline version is older
than 18 June 2001 and if the parameter modelootcorr is set to
true (the default). The PPSVERS keyword is written by pipeline modules and
not by the SAS proc routines; this means that if the data is
reprocessed to create new event files then this keyword will not be present.
If arfgen
does not find the keyword it issues a warning. This should
be ignored if the event file has been created with SAS 5.3 or any SAS
version not older than 18 June 2001.
A PN ARF would be decreased by the following amount:
Mode |
Factor (%) |
PRIME_FULL_WINDOW |
6.2 |
PRIME_FULL_WINDOW_EXTENDED |
2.3 |
PRIME_SMALL_WINDOW |
1.1 |
XMM-Newton SOC -- 2023-04-16