GRB 160802A

V. Bhalerao (IUCAA), V. Kumar (IUCAA), D. Bhattacharya (IUCAA), A. R. Rao (TIFR), S. Vadawale (PRL) report on behalf of the Astrosat CZTI collaboration:

Analysis of Astrosat data showed the CZTI detection of a very bright GRB160802A (Fermi-GBM detection: E. Bissaldi et al., GCN Circ. 19754
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 ).

The source was clearly detected in the 40-200 keV energy range. The light curve shows a complex structure, with the strongest peak at 06:13:30.90 UT, 0.27
seconds after Fermi Trigger at 06:13:29.63 UT and a peak count rate of 4270.0 counts/sec above the background (four quadrants summed together), with a total
of 91636 counts. The local mean background count rate was 310.0 counts/sec. Using cumulative rates, we measure a T90 of 16.8 secs.

CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb . CZTI is built by a TIFR-led consortium of
institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.

T. Tamura (Kanagawa U), A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama,
Y. Yamada (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), I. Takahashi (IPMU),
Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu (Kanagawa U), W. Ishizaki (ICRR),
M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The long-duration GRB 160802A (Bissaldi et al., GCN Circ. 19754
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 ;
Panasyuk et al., GCN Circ. 19759
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 ; Kozlova et al., GCN Circ. 19767
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 )
triggered the CALET Gamma-ray Burst Monitor (CGBM) at 6:13:28.85 on
2 August 2016.  The burst signal was seen by all CGBM instruments.

The light curve of the SGM shows two episodes.  The first episode
has a FRED-like structure with several pulses.  The emission starts
at T0 and ends at T+7 sec.  The second episode starts at T+17 sec,
peaks at T+18 sec and ends at T+22 sec.  The T90 duration measured by the
SGM data is 16.1 +- 0.1 sec (40-1000 keV).

The light curve is available at

http://cgbm.calet.jp/cgbm_trigger/flight/1154153496/

The CALET data used in this analysis are provided by the Waseda
CALET Operation Center located at the Waseda University.

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 long-duration bright GRB 160802A
(Fermi GBM observation: Bissaldi, GCN 19754
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 ;
Lomonosov BDRG GRBM detection: Panasyuk et al., GCN 19759
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 ;
IPN triangulation: Hurley et al., GCN 19766
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  )
triggered Konus-Wind at T0=22409.945 s UT (06:13:29.945).

The burst light curve shows a multipeaked structure
started at ~T0-0.1 s with a total duration of ~20.0 s.
The emission is seen up to ~3 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB160802_T22409/

As observed by Konus-Wind, the burst
had a fluence of 8.37(-0.47,+0.50)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+0.976 s,
of 3.27(-0.41,+0.42)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+20.224 s)
is best fit in the 20 keV - 3 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.74(-0.05,+0.05),
the high energy photon index beta = -2.43(-0.12,+0.10),
the peak energy Ep = 273(-14,+15) keV
(chi2 = 111/68 dof)

The spectrum near the maximum count rate
(measured from T0+0.768 to T0+1.280 s)
is best fit in the 20 keV - 3 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.14(-0.14,+0.15),
the high energy photon index beta = -2.42(-0.24,+0.16),
the peak energy Ep = 306(-30,+36) keV
(chi2 = 73/51 dof)

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

K. Hurley, on behalf of the IPN,

I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin,
on behalf of the HEND-Odyssey GRB team,

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

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

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:

The bright long-duration GRB 160802A has been detected by
Fermi (GBM: Bissaldi, GCN Circ. 19754
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 ), Konus-Wind, Mars-Odyssey (HEND),
and INTEGRAL (SPI-ACS), so far, at about 22410 s UT (06:13:30).

We have triangulated it to a preliminary, 3 sigma error box whose
coordinates are:
 ---------------------------------------------
  RA(2000), deg                 Dec(2000), deg
 ---------------------------------------------
 Center:
   28.027 (01h 52m 07s) +71.370 (+71d 22' 10")
 Corners:
   26.646 (01h 46m 35s) +71.433 (+71d 26' 00")
   28.172 (01h 52m 41s) +71.786 (+71d 47' 09")
   29.401 (01h 57m 36s) +71.295 (+71d 17' 41")
   27.891 (01h 51m 34s) +70.952 (+70d 57' 08")
 ---------------------------------------------
The error box area is 1343 sq. arcmin, and its maximum
dimension is 53 arcmin (the minimum one is 36 arcmin).
The Sun distance was about 78 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB160802_T22409/IPN/

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

M.I.Panasyuk, S.I.Svertilov, V.V.Bogomolov, A.M.Amelushkin, V.O.Barinova, 
A.V.Bogomolov, A.F.Iyudin, V.V.Kalegaev, D.Nguen,  V.L. Petrov, 
I.V.Yashin
Physics Department, Skobel`tsyn Institute of Nuclear Physics, Moscow State

V. Lipunov, E.S. Gorbovskoy, N.Tyurina
Lomonosov Moscow State University, Sternberg Astronomical Institute

I. Park, J. Lee, S. Jeong
Department of Physics, Sungkyunkwan University, Seobu-ro, Jangangu, 
Suwonsi, Korea

At 06:13:29.30 UT on 02 Aug 2016, the Lomonosov BDRG  Gamma-ray Burst 
Monitor  (http://lomonosov.sinp.msu.ru/en/scientific-equipment-2/bdrg )
triggered GRB 160802A (Bissaldi, GCN 19754
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 ).
GRB 160802A has  complicated LC, two peaks, total duration 20s duration,
with peak intensity >30 photons/cm2*s in the range 20-300 keV.
This Notice was ground-generated.
The message may be cited.

E. Bissaldi (Politecnico & INFN Bari)
reports on behalf of the Fermi GBM Team:


"At 06:13:29.63 UT on 02 August 2016, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 160802A (trigger 491811213 / 160802259).
The on-ground calculated location, using the GBM trigger data, is

RA, Dec =  35.29, +72.69

(J2000 degrees, equivalent to 02h 21m, 72d 41'),
with an uncertainty of 1 degree (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 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 GBM ground location is 106 degrees.

The GBM light curve consists of 2 FRED-like peaks
with a duration (T90) of about 16.4 s (50-300 keV).
The time-averaged spectrum from T0-0.3 s to T0+19.4 s is
best fit by a Band function with Epeak = 284 +/- 7 keV,
alpha = -0.71 +/- 0.02, and beta = -2.44 +/- 0.06.

The event fluence (10-1000 keV) in this time interval is
(1.04 +/- 0.08)E-04 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.7 s in the 10-1000 keV band
is 72.5 +/- 0.7 ph/s/cm^2.


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