An invocation of hkgtigen
for a particular instrument does generate
a GTI which covers the duration of the entire observation. This does not
exclude the possibility to apply this GTI data set to single-exposure
event lists. GTIs outside the exposure will simply have no effect
in the filtering process.
The proposed scheme does not exclude the possibility
to perform event list filtering with HK parameter GTIs from different
instruments. For doing this, please construct the GTI sets for all
desired instruments (e.g. gti_om.ds, gti_emos1.ds, gti_sc.ds)
and combine them in the selection expression that drives the filtering
process in task evselect:
evselect table=ev.ds expression="TIME in gti(gti_emos1.ds) && \
TIME in gti(gti_om.ds) && TIME in gti(gti_sc.ds)" ...