[AAVSO-HEN] GRB 090117B : Fermi GBM detection

[grb at aavso.org]

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TITLE:   GCN CIRCULAR
NUMBER:  8824
SUBJECT: GRB 090117B : Fermi GBM detection
DATE:    09/01/18 12:31:04 GMT
FROM:    Andreas von Kienlin at MPE  <azk at mpe.mpg.de>

Andreas von Kienlin (MPE) reports on behalf of the Fermi GBM Team:

"At 08:02:02.23 UT on 17 January 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090117B (trigger 253872124  / 090117335)
The on-ground calculated location, using the GBM trigger
data, is RA = 232.9, DEC = 27.6  (J2000 degrees,
equivalent to 15h 32m, 27d 36'), with an uncertainty
of 9.4 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which is currently estimated to be 2 to 3 degrees)
 
The angle from the Fermi LAT boresight is 49 degrees

The GBM light curve consists of two separate peaks,
the first from T0-0.768 to T0+0.768 sec and the second
from T0+24.0643 sec to T0+26.368 sec. T90 (8-1000 keV)
is about 27 sec. Both peaks were fit using a power-law function
with index -1.55 +/- 0.08 (chi squared 272.27/245 d.o.f.)
for the first and with index -1.55 +/- 0.07
(chi squared 249.72/245 d.o.f.)for the second peak.

The event fluence (8-1000 keV) for both peaks is
(2.1 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-0.768 s in the 8-1000 keV band
is 4.6 +/- 0.2 ph/s/cm^2

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