GRB 171011B

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,

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

S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT 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, very bright GRB 171011B was detected
by Konus-Wind, INTEGRAL (SPI-ACS), Mars-Odyssey (HEND),
and Swift (BAT) at about 3935 s UT (01:05:35).
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:
   158.860 (10h 35m 26s)  +1.646 ( +1d 38' 46")
  Corners:
   159.793 (10h 39m 10s)  -2.035 ( -2d 02' 06")
   158.437 (10h 33m 45s)  +4.418 ( +4d 25' 05")
   158.940 (10h 35m 46s)  +6.060 ( +6d 03' 36")
   159.687 (10h 38m 45s)  -0.726 ( +0d 43' 33")
  ---------------------------------------------
The error box area is 2.646 sq. deg, and its maximum
dimension is 8.14 deg (the minimum one is 23.5 arcmin).
The Sun distance was 37 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB171011_T03931/IPN

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

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, very intense GRB 171011B
(IPN triangulation: Hurley et al., GCN Circ. 21998
Loading...
 
 )
triggered Konus-Wind at T0=3931.430 s UT (01:05:31.430).

The burst light curve shows a multipeaked structure
which starts at ~T0-7.3 s and has a total duration of ~18.2 s.
The emission is seen up to ~20 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB171011_T03931/

As observed by Konus-Wind, the burst
had a fluence of 7.02(-0.56,+0.57)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+1.456 s,
of 5.55(-0.61,+0.62)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+10.496 s)
is best fit in the 20 keV - 20 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.54(-0.12,+0.14),
the high energy photon index beta = -2.28(-0.16,+0.12),
the peak energy Ep = 315(-33,+37) keV
(chi2 = 98/97 dof).

The spectrum near the maximum count rate
(measured from T0+0.256 to T0+1.792 s)
is best fit in the 20 keV - 20 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.51(-0.11,+0.14),
the high energy photon index beta = -2.59(-0.34,+0.21),
the peak energy Ep = 416(-48,+50) keV
(chi2 = 78/65 dof).

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

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

The long-duration GRB 171011B (Hurley et al., GCN Circ. 21998
Loading...
 
 ;
Svinkin et al., GCN Circ. 22005
Loading...
 
 ) triggered the CALET Gamma-ray Burst Monitor (CGBM)
at 01:05:36.47 on 11 October 2017.  The burst signal was seen by the all CGBM instruments.

The light curve of the SGM shows a single peak.  The emission starts at T0 sec
and the brightest pulse peaks at T+1.5 sec.  The entire emission ends at T+3.5 sec.
The T90 duration measured by the SGM data is 2.0 +- 0.3 sec (40-1000 keV).

The light curve is available at

http://cgbm.calet.jp/cgbm_trigger/flight/1191719089/

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

J. Zhang, J. Y. Liao, C. K. Li, X. B. Li, Y. Huang, S. L. Xiong, 
C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, X. F. Lu, J. L. Zhao, 
C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU),
F. J. Lu, L. M. Song, H. Y. Wang, M. Wu, Y. P. Xu, 
A. M. Zhang, Y. F. Zhang, S. N. Zhang (IHEP),
report on behalf of the Insight-HXMT team:


During the commissioning phase, at 2017-10-11T01:05:36 (T0),
Insight-HXMT/HE detected GRB 171011B (trigger ID: HEB171011045)
in a routine search of the data, which is also detected by CALET
(Marrocchesi et al., GCN 22022
Loading...
 
 ) and INTEGRAL, etc. 
This burst has been localized by IPN triangulation
(Hurley et al., GCN Circ. 21998
Loading...
 
 ).


The Insight-HXMT light curve consists of multi-pulses
with a duration (T90) of 1.6 s measured from T0+1.3 s to T0+2.9 s.
The 20-ms peak rate, measured from T0+1.98 s, is 23852.4 cnts/sec.
The total counts from this burst is 19179.3 counts.


URL_LC: http://www.hxmt.org/images/GRB/HEB171011B_LC.pdf


The time-averaged spectrum from T0-1 s to T0+7 s is
adequately fit by a Band spectrum with alpha = 3.94 +/- 0.86, 
beta = -2.65 +/- 0.16 and E_peak = 339.29 +/- 19.71.
The energy fluence is (5.45 +/- 0.24)E-05 erg/cm^2 in 200 - 5000 keV 
in this time interval.


All measurements above are made with the CsI detectors operating in the 
regular mode with the energy range of about 80-800 keV (record energy).
Only gamma-rays with energy greater than about 200 keV can penetrate
the spacecraft and leave signals in the CsI detectors installed inside 
of the telescope.


The analysis results presented above are preliminary;
final results will be published elsewhere.


Insight-HXMT is the first Chinese space X-ray telescope, which was funded
jointly by the China National Space Administration (CNSA) and the Chinese
Academy of Sciences (CAS). More information about it could be found at: 
http://www.hxmt.org/index.php/enhome .