GRB 160720A
GCN Circular 19741
Subject
GRB160720A: Astrosat CZTI detection
Date
2016-07-29T04:25:22Z (10 years ago)
From
Varun Bhalerao at IUCAA <varunb@iucaa.in>
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 GRB 160720A (Fermi-GBM detection: Hamburg and Burns, GCN Circ. 19724).
The source was clearly detected in the 40-200 keV energy range. The light curve shows a complex structure, with the strongest peak at 18:25:25 UT, 88 seconds after Fermi Trigger at 18:23:57.00 UT and a peak count rate of 318.0 counts/sec above the background (four quadrants summed together), with a total of 1813.0 counts. The local mean background count rate was 283.0 counts/sec. Using cumulative rates, we measure a T90 of 21.0 secs.
The center of the IPN Triangulation region (Hurley et al., GCN Circ. 19726) is at an angle of 143 degrees from the CZTI pointing direction.
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.
GCN Circular 19729
Subject
GRB 160720A CALET Gamma-Ray Burst Monitor detection
Date
2016-07-23T02:03:16Z (10 years ago)
From
Takanori Sakamoto at AGU <tsakamoto@phys.aoyama.ac.jp>
S. Ozawa (Wasoeda 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. Torii (Waseda U), Y. Shimizu, T. Tamura (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 160720A (Hamburg, et al., GCN circ. 19724;
Hurley, et al., GCN circ. 19726; Svinkin, et al. GCN circ. 19727;
Amelushkin, et al. GCN circ. 19728) triggered the CALET Gamma-ray
Burst Monitor (CGBM) at 18:25:16.38 on 20 July 2016. No real time CGBM
GCN notice was distributed about this trigger because the real time
communication from the ISS was off (loss of signal) between 17:57 and
18:45. The burst signal was seen by all CGBM instruments.
The light curve of the SGM shows two main peaks. The emission starts at
T-5 sec and ends at T+30 sec. The peak times of the main pulses are T+3 sec
and T+10 sec. The 3rd weak peak is visible at T+18 sec. The T90 duration
measured by the SGM data is 36.4 +- 1.7 sec (40-1000 keV).
The light curve is available at
http://cgbm.calet.jp/cgbm_trigger/flight/1153074224/
The CALET data used in this analysis are provided by the Waseda
CALET Operation Center located at the Waseda University.
GCN Circular 19728
Subject
GRB 160720A: Lomonosov BDRG gamma ray detection and MASTER limit
Date
2016-07-21T20:28:26Z (10 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
A.M.Amelushkin, V.O.Barinova, A.V.Bogomolov, V.V.Bogomolov, A.F.Iyudin,
V.V.Kalegaev, M.I.Panasyuk, V.L. Petrov, S.I.Svertilov, I.V.Yashin
Physics Department, Skobel`tsyn Institute of Nuclear Physics, Moscow State
University.
I. Park, J. Lee, S. Jeong
Department of Physics, Sungkyunkwan University, Seobu-ro, Jangangu,
Suwonsi, Korea
V. Lipunov, E.S. Gorbovskoy, N.Tyurina, V.Kornilov,
P.Balanutsa, A.Kuznetsov, D.Kuvshinov,
Lomonosov Moscow State University, Sternberg Astronomical Institute
R. Rebolo, M. Serra Ricart, N. Lodieu, G. Israelian
The Instituto de Astrofisica de Canarias
At 18:23:55.00 UT on 20 July 2016, the Lomonosov BDRG Gamma-ray Burst
Monitor (http://lomonosov.sinp.msu.ru/en/scientific-equipment-2/bdrg )
triggered GRB 160720A (Hamburg and Burns, GCN 19724).
GRB 160720A has complicated LC, duration >87s, very
with intensive peak between 18:25:12 - 18:25:22 .
Peak intensity >30 photons/cm2*s in the range 10-800 s.
This Notice was ground-generated.
MASTER-IAC robotic telescope (MASTER-Net: http://observ.pereplet.ru)
located in IAC (Tenerife) was cavered IPN error box (Hurley et al GCN
19726) GRB160720A error-box 23696 sec
after notice time and 30794 sec after trigger time at 2016-07-21 02:57:11
UT. The weather is determined by Sahara dust. The 5-sigma upper limit
is about 16.5 mag.
The message may be cited.
GCN Circular 19727
Subject
Konus-Wind observation of GRB 160720A
Date
2016-07-21T18:15:18Z (10 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik,
M. Ulanov, A. Tsvetkova, A. Lysenko, A. Kozlova, and T. Cline
on behalf of the Konus-Wind team, report:
The long-duration GRB 160720A
(Fermi-GBM detection: Hamburg and Burns, GCN Circ. 19724;
IPN triangulation: Hurley et al., GCN Circ. 19726)
triggered Konus-Wind at T0=66314.254 s UT (18:25:14.254).
The burst light curve shows a multipeaked structure
started at ~T0-80 s with a total duration of ~160 s.
The emission is seen up to ~2 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB160720_T66314/
As observed by Konus-Wind, the burst
had a fluence of 1.50(-0.05,+0.05)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+10.288 s,
of 1.31(-0.16,+0.16)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the most intense part
(measured from T0 to T0+27.392 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 = -0.87(-0.04,+0.04),
the high energy photon index beta = -2.87(-0.18,+0.14),
the peak energy Ep = 227(-8,+9) keV
(chi2 = 108/75 dof)
The spectrum near the maximum count rate
(measured from T0+9.728 to T0+10.496 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 = -0.82(-0.08,+0.09)
and Ep = 328(-28,+32) keV (chi2 = 66/54 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.7
(chi2 = 66/53 dof)
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 19726
Subject
IPN Triangulation of GRB 160720A
Date
2016-07-21T17:47:24Z (10 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
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,
D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova,
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 long-duration GRB 160720A (Hamburg and Burns, GCN Circ. 19724) has
been detected by Fermi (GBM), Konus-Wind, INTEGRAL (SPI-ACS), and
Mars-Odyssey (HEND), so far, at about 66237 s UT (18:23:57).
We have triangulated it to a preliminary, 3 sigma error box whose
coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
58.153 (03h 52m 37s) +73.893 (+73d 53' 33")
Corners:
62.806 (04h 11m 13s) +74.084 (+74d 05' 01")
53.505 (03h 34m 01s) +74.329 (+74d 19' 44")
53.637 (03h 34m 33s) +73.582 (+73d 34' 56")
62.531 (04h 10m 07s) +73.338 (+73d 20' 17")
---------------------------------------------
The error box area is 1.9 sq. deg, and its maximum
dimension is 2.7 deg (the minimum one is 44.8 arcmin).
The Sun distance was 61 deg.
This box may be improved.
A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB160720_T66314/IPN/
The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.
GCN Circular 19724
Subject
GRB 160720A: Fermi GBM detection
Date
2016-07-21T01:53:43Z (10 years ago)
From
Rachel Hamburg at UAH <rkh0007@uah.edu>
R. Hamburg (UAH) and E. Burns (UAH)
report on behalf of the Fermi GBM Team:
"At 18:23:57.00 UT on 20 July 2016, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 160720A (trigger 490731840 / 160720767).
The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 43, Dec = +76, with a statistical uncertainty of 1.00 degrees;
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 is 131 degrees.
The GBM light curve consists of several overlapping peaks with a duration
(T90)
of about 79 s (50-300 keV). The time-averaged spectrum from T0-1.02 to
T0+154 s is best fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.12 +/- 0.01 and
the cutoff energy, parameterized as Epeak, is 191 +/- 3 keV.
The event fluence (10-1000 keV) in this time interval is (151 +/- 1)E-06
erg/cm^2. The 1-sec peak photon flux measured starting from T0+88 s in the
10-1000 keV band is 58 +/- 1 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."