We have applied this method to GRB970517 (BATSE 6235). We chose this GRB
for its characteristics of intensity, morphology and relative intensities registered in
different detectors: it is a strong, sharp burst lasting about 5 s, with approximately
the same signal in detectors GRBM2 and GRBM3. In this preliminary attempt, we used
BATSE data to derive its spectral properties (spectral index
, assuming a
power-law spectrum
). As a preliminary determination of the GRB
incoming direction we have only considered the ratio between the GRBM2 and GRBM3
intensities, whose
dependence on the azimuth
is shown in Fig. 1. The
comparison between observed and expected ratio gives a strong selection of the possible
values of
as a function of the altitude
. The same criterion has been
used to select a combination of detectors intensities giving a good selection of
versus
. The ratio between the sum of detectors GRBM1
and GRBM4 and the sum of detectors GRBM2 and GRBM3 proved to give the best results.
Both computations were carried out for the two GRBM spectral bands (GRBM band,
40-700 keV and AC band, 100-700 keV).
The final error box is shown in Fig. 2 along with BATSE's position.
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