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##

The Data Archive Coverage

At the Physics Department of the University of Ferrara (Italy),
a near-complete version of the GRBM data archive is continuously
maintained and updated by the high energy astrophysics team
by means of a proper software, the GRBMS.

The current situation (October 2001) of the GRBM archive can be
summarized in terms of observation time: we limit our attention
only to the normal OPs, starting from July 1996, when the first OPs with
regular scientific data became available:
while the total time elapsed is 1919 days, i.e. x s,
the total time duration of all the normal OPs is x s:
thus, it comes out that the fraction of time elapsed in normal
pointing mode is 81% of the whole time interval.
The total time of the overall set of OPs currently available
is x s, i.e. 87% of the total duration
of the normal OPs.

The hole in the current data archive, represented by the
lacking OPs with normal pointings, that amount to 13% of
the whole normal pointing observation time, is going to be filled in,
in collaboration with the SDC people.

Currently, we conclude that the total time coverage of the overall
set of OPs with normal pointing (i.e., with fixed satellite attitude)
presently available in our GRBM archive is
70% out of the total time elapsed since July 1996.
Furthermore, out of this 70%, the time spent in the nearby of the SAGA,
during which the GRBM HVs are periodically switched off
( 15-20 min/orbit), has to be excluded;
therefore, by assuming an average time of 18 min/orbit
spent over the SAGA, which looks quite reasonable, the corresponding
fraction comes out to be 17-18% per orbit: thus, only for the 82-83%
out the 70%, that is 57-58% out of the total elapsed time is
covered by 1 s ratemeters, currently available in our GRBM data
archive.

This fraction is needed for estimating the
sky exposure of the GRBM and, therefore, particularly for estimating
the mean GRB rate as measured with GRBM (sec. ).

** Next:** Directions of GRBs with
** Up:** The GRBM Archive
** Previous:** OBT-UT Conversion
** Contents**
Cristiano Guidorzi
2003-07-31