During the time interval scanned by the off-line quest, i.e.
July 3, 1996 - October 3, 2001, the on-board logic was triggered
by 15,857 events; out of them, after this off-line quest,
only 693 could not have been scanned, because of the proximity
to data gaps, mainly connected with the SAGA (this number,
i.e. 693, is smaller than the 1032 taken in
sec. , because that
was for the 1 s quest only: in this case, the number is smaller
because several on-board triggers missed by one particular quest,
have been scanned with other rebin times, instead; therefore, the final
number of 693 unscanned on-board triggers refer to those events,
that could not have been scanned by any quest).
Thus, if one takes into account only those on-board triggers that
have been scanned by at least one kind of off-line quest
(1 s, 2 s, 4 s, or 8 s, resp.), i.e.
15,857 - 693 = 15,164 triggers, the reliability
of the
on-board trigger logic can be defined as the ratio of the
number of true GRBs that triggered the GRBM on board, over the
number of scanned on-board triggers:
The estimate coming out from eq. relies
on the assumption that all the on-board triggers that
have been automatically scanned by the off-line quest and that
have not been classified as GRBs, cannot be GRBs.
On the other hand, from table
, it is known
that there are at least 5 exceptions (4 in common with BATSE
and 1 with one WFC); however,
in the next sections, when dealing with the common sample with BATSE,
it will be shown that this fraction still remains negligible, so
that the above assumption is still reasonable.