[vsnet-grb-info 20137] GRB 171210A: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22233
SUBJECT: GRB 171210A: Fermi GBM detection
DATE:    17/12/11 04:12:12 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076 at uah.edu>

S. Poolakkil (UAH), C. Meegan (UAH) and A. von Kienlin (MPE) report on
behalf of the Fermi GBM Team:

"At 11:49:15.26 UT on 10 December 2017, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 171210A (trigger 534599360 / 171210493)
which was also detected by the Fermi LAT (E. Bissaldi et al. 2017, GCN
22228). The GBM on-ground
location is consistent with the LAT position.

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 initial angle from the Fermi LAT boresight to
the best location is 51 degrees.

The GBM light curve consists of a single bright peak
with a duration (T90) of about 143 s (50-300 keV).
The time-averaged spectrum from T0-1.02 s to T0+103.42 s is
best fit by a Band function with Epeak= 145 +/- 3 keV, alpha = -0.65 +/-
0.02
and beta = -2.34 +/- 0.05.

The event fluence (10-1000 keV) in this time interval is
(7.33 +/- 0.08)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+6.46 s in the 10-1000 keV band
is 16.7 +/- 0.36 ph/s/cm^2.

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