GRB 160822, GRB 160822A

A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:

The short-duration GRB 160822A
(Fermi GBM detection: Hamburg et al., GCN Circ. 19845
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 ;
IPN triangulation: Svinkin et al., GCN Circ. 19852
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 )
triggered Konus-Wind at T0=58061.153 s UT (16:07:41.153).

The burst light curve shows a single pulse
which starts at T0-0.016 s with a total duration of 0.03 s.
The emission is seen up to ~10 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB160822_T58061/

As observed by Konus-Wind, the burst
had a fluence of 7.60(-1.87,+5.46)x10^-7 erg/cm2,
and a 16-ms peak flux, measured from T0-0.006 s,
of 3.95(-1.40,+4.02)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The spectrum of the burst
(measured from T0 to T0+0.064 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.59 (-0.75,+1.34)
and Ep = 599 (-222,+2249) keV (chi2 = 11/14 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -1.9
(chi2 = 11/13 dof)

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova,
and T. Cline on behalf of the Konus-Wind team,

K. Hurley, on behalf of the IPN,

V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa,
and A. Goldstein, on behalf of the Fermi GBM team,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

and

S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team, report:

The short-duration, hard-spectrum, bright GRB 160822A has been detected 
by Fermi (GBM; Hamburg et al., GCN Circ. 19845
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 ), Konus-Wind, INTEGRAL 
(SPI-ACS), and Swift (BAT) at about 58060 s UT (16:07:40). The burst was 
outside the coded field of view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box whose
coordinates are:
---------------------------------------------
    RA(2000), deg                 Dec(2000), deg
   ---------------------------------------------
   Center:
    272.129 (18h 08m 31s)  +3.584 ( +3d 35' 01")
   Corners:
    272.065 (18h 08m 16s)  +1.771 ( +1d 46' 15")
    271.809 (18h 07m 14s)  +1.779 ( +1d 46' 45")
    272.205 (18h 08m 49s)  +5.396 ( +5d 23' 45")
    272.462 (18h 09m 51s)  +5.389 ( +5d 23' 19")
   ---------------------------------------------
The error box area is 3348 sq. arcmin, and its maximum
dimension is 3.67 deg (the minimum one is 15.4 arcmin).
The Sun distance was 118 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB160822_T58061/IPN/

The Konus-Wind time history and spectrum will be given in forthcoming 
GCN Circulars.

R. Hamburg (UAH), C. Meegan (UAH), and A. Goldstein (USRA)
report on behalf of the Fermi GBM Team:

"At 16:07:40.01 UT on 22 August 2016, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 160822A (trigger 493574864 / 160822672).

The on-ground calculated location, using the GBM trigger
data, is RA = 270, DEC = +8, with an uncertainty
of 5 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

The angle from the Fermi LAT boresight at the GBM trigger time is 58
degrees.

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 on-board
localization, 160 degrees from the LAT boresight.  The more reliable
on-ground
localization placed the GRB at a location ~100 deg away from the onboard
localization.  The ARR was then canceled and replaced with a short TOO
at the on-ground localization.

The GBM light curve shows a single peak
with a duration (T90) of about 0.4 s (50-300 keV).
The time-averaged spectrum from T0-0.13 s to T0+0.13 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.05 +/- 0.10 and
the cutoff energy, parameterized as Epeak, is 1166.00 +/- 560.00 keV.

The event fluence (10-1000 keV) in this time interval is
(7.33 +/- 0.49)E-07 erg/cm^2. The 0.064-sec peak photon flux measured
starting from T0+0.0 s in the 10-1000 keV band
is 22 +/- 2 ph/s/cm^2.

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