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: http://xmm.vilspa.esa.es/sas/6.5.0/doc/lccorr/node17.html
Дата изменения: Tue Aug 16 09:00:09 2005 Дата индексирования: Sat Dec 22 08:42:07 2007 Кодировка: |
So far the discussion has assumed that the `source' time series is a record of events from a point-like source of x-rays. However it may be convenient also to be able to correct time series which arise from phenomena that are not spatially localized. Background events, whether arising from true x-rays or from energetic particles which have collided with the detector, are one example of such. For such a time series, it is clearly inappropriate to use the point-source PSF to calculate the fraction of events lost to non-live areas of the detector. Ideally lccorr would allow the user to provide an image of the source. Such a facility is planned, but at present all that can be done is to allow the user to provide a list of weights which gives the fraction of the events received onto each of the CCDs of the detector. The mode is accessed via the parameters srcweightstyle and srcweightsnode0. A typical call of lccorr in this non-point-source mode might be as follows:
lccorr eventset=<MOS evlist name> srctsset=<src ts name> withbkgtsset=no
srcweightstyle=user srcweights='1.2 1.0 1.0 1.0 1.0 1.0 1.0'
To avoid breaking users' scripts, the default behaviour of lccorr if these new parameters srcweightstyle and srcweightsnode0 are omitted has been left exactly the same as before.
Note that events lost to vignetting, to absorption by the filter or to quantum inefficiency cannot be estimated in this mode: only time-dependent corrections can be made. Hence the parameters treatvignet, treatfiltertrans and treatquantumeff have no effect.