Gamma-ray Burst 160720A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN Circular #19724
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."
GCN Circular #19725
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 Lomonosov Moscow State University, Physics Department, Skobeltsyn Institute of Nuclear Physics, Moscow, Russia
E.S. Gorbovskoy, V.G.Kornilov, V.M. Lipunov Lomonosov Moscow State University, Physics Department, Sternberg Astronomical Institute of M.V. Lomonosov Moscow, Moscow, Russia
I. Park, J. Lee, S. Jeong Department of Physics, Sungkyunkwan University, Seobu-ro, Jangangu, Suwonsi, Korea
Russian space mission "Lomonosov" (*) ( http://lomonosov.sinp.msu.ru/en/ ) was launched 28.04.2016 from new Russian Kosmodrom "Vostochny" to polar solar-synchronous orbit with altitude ~490 km. Scientific program of "Lomonosov" includes a multi-wavelength GRB study at different time scales. In particular the complex study of prompt emission will be provided based on the direct recording of readings of wide field optical cameras as well as on the fast pointing of optical and UV telescope using its moving mirror. The spacecraft "Lomonosov" contains 3 instruments for GRB study: gamma-ray burst monitor BDRG ( http://lomonosov.sinp.msu.ru/en/scientific-equipment-2/bdrg ), a wide field optical camera SHOK ( http://lomonosov.sinp.msu.ru/en/scientific-equipment-2/shok ) and UFFO ( http://lomonosov.sinp.msu.ru/en/scientific-equipment-2/uffo ) instrument consisting of coding mask X-ray telescope UBAT and UV slewing mirror telescope SMT.
The Lomonosov GRB monitor BDRG is designed to obtain temporal and spectral information about GRBs in energy range 10-3000 keV as well as to produce GRB trigger.
The trigger is used onboard to fix some amount of data before GRB stored in the internal memory of all instruments of GRB complex as well as to start the detailed data collection. Immediately after the trigger the onboard estimation of the GRB position starts. Then the telegram with trigger information is sent via Global Star transmitter to the server in MSU and, after automatic ground-based data processing (to exclude radiation belt zones etc.) to GCN (this will be realized sometime later after optimizing the trigger parameters during flight tests).
There are 3 GRBs and 5 SGR outbursts are detected to the present BDRG GRB monitor, which were also detected by other space missions and presented in GCN:
GRB 160703 12:10:02 UTC
GRB 160705 17:40:19 UTC
GRB 160720 18:27:55 UTC
Bursts from SGR1935+2154
```
18.06.2016 20:27:24 UTC,
20.06.2016 15:16:34 UTC, 
23.06.2016 21:20:45 UTC,
23.06.2016 21:23:35 UTC,
26.06.2016 13:54:29 UTC
```
Press release is available at http://lomonosov.sinp.msu.ru/wp-content/uploads/GRB_by_BDRG_engl_pdf.pdf
The message may be cited.
(*) About M.V.Lomonosov https://en.wikipedia.org/wiki/Mikhail_Lomonosov
GCN Circular #19726
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 #19727
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 #19728
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.
GCN Circular #19729
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 #19741
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.

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Jochen Greiner, last update: 29-Jul-2016 [Disclaimer]