GRB 161020A

S.Mereghetti (IASF-Milano), V. Savchenko (APC, Paris), D.Gotz (CEA, 
Saclay), C.Ferrigno (ISDC, Versoix), and J.Borkowski (CAMK, Torun) on 
behalf of the IBAS Localization Team report:

a gamma ray burst lasting about 15 s has been detected by IBAS in the 
IBIS/ISGRI data at 00:34:40 UT of 2016 October 20. This burst was also 
detected by Fermi/GBM (trigger num. 498616490).

The burst occurred immediately after the end of a slew of the INTEGRAL 
satellite. For this reason the corresponding IBAS Alert was not 
distributed in real time.

From an offline analysis we derived the burst coordinates (J2000):

R.A.=  161.0309 deg
DEC.=  -54.7687 deg

with an uncertainty of about 2 arcmin (90% c.l.).

The burst had a peak flux of 0.8 counts/cm2/s (20-200 keV, 1-s integration 
time) and a fluence in the same energy range of about 4e-7 erg/cmq.

A plot of the light curve will be posted at 
http://ibas.iasf-milano.inaf.it/IBAS_Results.html

C. M. Hui (NASA/MSFC), C Meegan (UAH), and P. Jenke (UAH)
report on behalf of the Fermi GBM Team:

At 00:34:46.95 UT on 20 October 2016, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 161020A (trigger 498616490/161020024),
which was also detected by INTEGRAL (Mereghetti et al., GCN 20086
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 ).
The GBM on-ground location is consistent with the INTEGRAL position.
The angle from the Fermi LAT boresight is 117 degrees.

The GBM light curve shows a single peak
with a duration (T90) of about 12.3 s (50-300 keV).
The time-averaged spectrum from T0-6.1 s to T0+3.1 s is adequately
fit by a simple power law function with index -1.74 +/- 0.05.

The event fluence (10-1000 keV) in this time interval is
(1.49 +/- 0.14)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-0.1s in the 10-1000 keV band is 2.3 +/- 0.2 ph/s/cm^2.

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