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GCN Circular 18229

GRB 150902A: Fermi GBM detection
2015-09-03T09:32:09Z (9 years ago)
Oliver Roberts at UCD/Fermi <>
O.J. Roberts (UCD) and G. Younes (GWU) report on behalf
of the Fermi GBM team:

"At 17:35:39 UT on September 2nd 2015, the Fermi
Gamma-Ray Burst Monitor triggered and located
GRB 150902A (trigger 462908143/150902733), which was
also detected by Fermi-LAT (Axelsson et al. 2015, GCN 18228).

The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software due to the high peak flux of the
GRB. This ARR was accepted and the spacecraft slewed to the
GBM in-flight location. Both the GBM in-flight and on-ground
locations are consistent with the LAT position.

The GBM light curve consists of a series of unresolved pulses,
with a duration of about 14 s (50-300 keV). The time-averaged
spectrum from T0+3.0s to T0+17.0s is well fit by a Band
function with Epeak = 351.40 +/- 5.61 keV, Alpha =-0.48 +/- 0.02
and Beta = -2.32 +/- 0.03.

The event fluence (10-1000 keV) in this time interval is
(8.221 +/- 0.043)E-05 erg/cm^2. The 1.024 s peak photon flux
measured starting from T0+8.8s in the 10-1000 keV band is
61.9 +/- 0.5 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
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