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: http://xmm.vilspa.esa.es/sas/5.4.1/doc/epchain/node7.html
Дата изменения: Fri Jan 10 23:58:50 2003 Дата индексирования: Sat Dec 22 08:11:45 2007 Кодировка: Поисковые слова: mercury surface |
If requested (runbackground=Y), the task also creates a background lightcurve for the imaging modes (FF, eFF, LW, SW) using background masks (these are not used for the fast modes as there is no useful background region, in this case the total lightcurve is produced). Depending on the individual observation and on the requested timebinsize one can then create a GTI file via tabgtigen (e.g.):
tabgtigen table=rate_bkg.fits gtiset=bkg_GTI.fits expression='COUNTS<200'or using the count rate column
tabgtigen table=rate_bkg.fits gtiset=bkg_GTI.fits expression='RATE<60'where the output rate is in counts ks
tabgtigen table=rate_bkg.fits gtiset=bkg_GTI.fits expression='RATE<6'The GTI file can then be used to screen the event list via evselect (e.g.)
evselect expression='GTI(bkg_GTI.fits,TIME)' ...As the GTIs strongly depend on the intended science this screening is not performed and only background masks, the lightcurve, and a GTI file are created by epchain. XMM-Newton SOC/SSC -- 2003-01-10