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Дата изменения: Wed Jul 2 03:00:45 2008
Дата индексирования: Fri Sep 5 19:41:31 2008
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XMM-Newton Science Analysis System


epreject (epreject-5.11) [xmmsas_20080701_1801-8.0.0]

Meta Index / Home Page / Description / Soft flare rejection for

Background: motivation for developing this procedure

The EPIC-pn fast timing mode was designed so that a time resolution of 0.029 milliseconds can be achieved. This mode is important for observing bright variable sources with a very high time resolution. Up to now the it has only been possible to use the spectra down to 300 eV in this mode. Below this energy the data is affected by so-called soft flares which are caused by stack overflows generated by high energy particles.

These so-called soft flares have sharp rise (from 0 counts/sec to several thousand counts/sec in $\sim$0.10-0.15 sec) then decaying back 0 counts/sec slightly slower in about 0.3-0.4 sec). In some cases (extremly bright flares) they can lead to a FIFO overflow thus causing a small gap in the data of about $\sim$0.08 sec. These gaps are not yet handled by the SAS.

In this task we provide a method to mitigate the effect these flares have on the data for flagging such soft flare events so that they can later be screened from the data by the epreject command in the epchain.

With this method it at last becomes possible to use the spectral information in the data down to the lowest energies detectable in this mode i.e. 200 eV.

This is particularly interesting for timing studies of isolated neutron stars, X-ray Binaries and other variable objects, such as magnetic CVs, with very soft spectra.