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GCN Circular 19411

Subject
GRB 160509A: Fermi GBM Detection
Date
2016-05-09T17:47:13Z (8 years ago)
From
Oliver Roberts at UCD/Fermi <oliver.roberts@ucd.ie>
O.J. Roberts (UCD), G. Fitzpatrick (UCD) and
P. Veres (UAH) report on behalf of the Fermi GBM Team:

"At 08:59:04.36 UT on 09 May 2016, the Fermi Gamma-Ray
Burst Monitor triggered and located GRB 160509A
(trigger 484477148/160509374). The trigger resulted in
an Autonomous Repoint Request (ARR) by the GBM Flight
Software owing to the high peak flux of the GRB. This
ARR was accepted and the spacecraft slewed to the GBM
in-flight location. The GRB was also detected by the
LAT (F. Longo et al. 2016, GCN 19403), MAXI/GSC
(Y. Ono et al. 2016, GCN 19404) and Swift XRT
(J.A. Kennea et al. 2016, GCN 19408). The GBM on-ground
location is consistent with these positions.

The angle from the Fermi LAT boresight at the GBM
trigger time using the LAT position, is 32 degrees.

The GBM light curve consists of multiple peaks
with a duration (T90) of about 371 s (50-300 keV).
The time-averaged spectrum from T0-1.5 s to T0+39.4 s is
best fit by a BAND function, with Epeak = 370 +/- 7 keV,
alpha = -0.89 +/- 0.01, and beta = -2.11 +/- 0.02.

The event fluence (10-1000 keV) in this time interval is
(1.51 +/- 0.01)E-04 erg/cm^2. The 1-sec peak photon flux
measured starting from T0+16.6 s in the 8-1000 keV band
is 75.5 +/- 0.6 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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