GRB 181028A
GCN Circular 23409
Subject
GRB 181028A: Insight-HXMT/HE detection
Date
2018-11-05T05:15:22Z (7 years ago)
From
Ce Cai at IHEP <caice@ihep.ac.cn>
C. Cai, C. K. Li, X. B. Li, G. Li, J. Y. Liao, S. L. Xiong,
C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, J. L. Zhao,
A. M. Zhang, Y. F. Zhang, X. F. Lu, 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, S. N. Zhang (IHEP),
report on behalf of the Insight-HXMT team:
At 2018-10-28T14:09:43.000 (T0), the Insight-HXMT/HE detected
GRB 181028A (trigger ID: HEB181028590) in a routine search of the data,
which was also triggered by Fermi/LAT (Axelsson et al.,GCN 23386);
Fermi/GBM (Bissaldi et al.,GCN 23387);
IPN Triangulation (Hurley et al.,GCN 23388);
Konus-Wind observation (Kozlova et al., GCN 23393);
CALET/GBM (A. Yoshida et al., GCN 23399).
The Insight-HXMT/HE light curve mainly consists of multiple
pulses with a duration (T90) of 23.58 s measured from T0-4.53 s.
The 1-s peak rate, measured from T0+14.63 s, is 1351.0 cnts/s.
The total counts from this burst is 11055.5 counts.
URL_LC: http://www.hxmt.org/images/GRB/HEB181028590_lc.jpg
All measurements above are made with the CsI detectors operating in the
GRB mode with the energy range of about 200-3000 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.
Insight-HXMT is the first Chinese space X-ray telescope, which was
fundedjointly by the China National Space Administration (CNSA) and
the Chinese Academy of Sciences (CAS).
More information could be found at: http://www.hxmt.org.
GCN Circular 23399
Subject
GRB 181028A: CALET Gamma-Ray Burst Monitor detection
Date
2018-10-31T11:40:37Z (7 years ago)
From
Valentin Pal'shin at AGU <val@phys.aoyama.ac.jp>
A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita, Y. Kawakubo,
A. Tezuka, S. Matsukawa, H. Onozawa, T. Ito, H. Morita, Y. Sone (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, P. S. Marrocchesi (U of Siena),
and the CALET collaboration:
The long GRB 181028A (Fermi-LAT detection: Axelsson et al., GCN Circ. 23386;
Fermi-GBM observation: Bissaldi & Meegan, GCN Circ. 23387;
IPN Triangulation: Hurley et al., GCN Circ. 23388;
Konus-Wind observation: Kozlova et al., GCN Circ. 23393)
triggered the CALET Gamma-ray Burst Monitor (CGBM) at 14:09:39.546 UTC
on 28 October 2018. The burst signal was seen by all CGBM detectors.
The burst light curve shows a multi-peaked structure
which starts at T+2.6 sec, peaks at T+14.4 sec, and ends at T+32.1 sec.
The T90 and the T50 durations measured by the SGM data are
25.4 +- 5.5 sec and 8.3 +- 0.9 sec (40-1000 keV), respectively.
The ground processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1224770949/
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at the Waseda University.
GCN Circular 23393
Subject
Konus-Wind observation of GRB 181028A
Date
2018-10-30T10:36:15Z (7 years ago)
From
Anna Kozlova at Ioffe Institute <ann_kozlova@mail.ioffe.ru>
A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:
The long-duration GRB 181028A
(Fermi-LAT detection: Axelsson et al., GCN Circ. 23386;
Fermi-GBM observation: Bissaldi & Meegan, GCN Circ. 23387;
IPN Triangulation: Hurley et al., GCN Circ. 23388)
triggered Konus-Wind at T0=50984.309 s UT (14:09:44.309).
The burst light curve shows a multipeaked structure
which starts at ~T0-2 s and has a total duration of ~38 s.
The emission is seen up to ~4 MeV.
As observed by Konus-Wind, the burst
had a fluence of 3.43(-0.18,+0.20)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+26.064 s,
of 4.06(-1.01,+1.03)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+40.704 s)
is best fit in the 20 keV - 4 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.72(-0.10,+0.11)
and Ep = 286(-22,+26) keV (chi2 = 53/70 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.6
(chi2 = 53/69 dof).
The spectrum near the maximum count rate
(measured from T0+24.320 to T0+32.512 s)
is best fit in the 20 keV - 4 MeV range
by a power law with exponential cutoff model
with alpha = -0.39(-0.23,+0.27)
and Ep = 292(-37,+49) keV (chi2 = 70/70 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.1
(chi2 = 70/69 dof).
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB181028_T50984/
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.
GCN Circular 23388
Subject
IPN Triangulation of GRB 181028A (long)
Date
2018-10-29T17:45:10Z (7 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,
A. Goldstein, M. S. Briggs, and C. Wilson-Hodge
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 181028A
(Fermi-LAT detection: Axelsson et al., GCN Circ. 23386;
Fermi-GBM detection: Bissaldi et al., GCN Circ. 23387)
was detected by Fermi (GBM trigger 562428587), Konus-Wind,
INTEGRAL (SPI-ACS), and Mars-Odyssey (HEND),
at about 50982 s UT (14:09:42).
We have triangulated it to a preliminary, 3 sigma error box whose
coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
88.889 (05h 55m 33s) -21.163 (-21d 09' 49")
Corners:
89.470 (05h 57m 53s) -21.496 (-21d 29' 47")
89.355 (05h 57m 25s) -22.345 (-22d 20' 42")
88.311 (05h 53m 15s) -20.824 (-20d 49' 27")
88.431 (05h 53m 43s) -19.956 (-19d 57' 23")
---------------------------------------------
The error box area is about 1.0 sq. deg, and its maximum
dimension is 2.539 deg (the minimum one is 33.12 arcmin).
The Sun distance was about 114 deg.
This box intersects the Fermi-LAT 90% CL error circle
(Axelsson et al., GCN Circ. 23386) to form an error box
whose area is about 4 times smaller than that of the LAT
error circle.
This box may be further improved.
A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB181028_T50984/IPN
The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.
GCN Circular 23387
Subject
GRB 181028A: Fermi GBM observation
Date
2018-10-29T16:03:48Z (7 years ago)
From
Elisabetta Bissaldi at INFN,Bari <elisabetta.bissaldi@ba.infn.it>
E. Bissaldi (Politecnico & INFN Bari) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:
"At 14:09:42.53 UT on 28 October 2018,
the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 181028A
(trigger 562428587/ 181028590),
which was also detected by the
Fermi-LAT (Axelsson et al. 2018, GCN 23386).
The GBM on-ground location is
consistent with the LAT position.
The angle from the Fermi-LAT boresight
at the GBM trigger time is 58 degrees.
The GBM light curve consists of multiple peaks
with a duration (T90) of about 30 s (50-300 keV).
The time-averaged spectrum from T0 to T0+30 s
is adequately by a power law function with
an exponential high-energy cutoff.
The power law index is -0.72 +/- 0.02 and
the cutoff energy, parameterized as Epeak,
is 326 +/- 10 keV.
The event fluence (10-1000 keV) in this time interval
is (3.35 +/- 0.05)E-05 erg/cm^2.
The 1-sec peak photon flux measured
starting from T0+26.5 s in the 10-1000 keV band
is 10.3 +/- 0.3 ph/s/cm^2.
A Band function fits the spectrum equally well
with Epeak= 306 +/- 13 keV, alpha = -0.69 +/- 0.03,
and beta = -2.66 +/- 0.24.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 23386
Subject
GRB 181028A: Fermi-LAT detection
Date
2018-10-29T00:05:28Z (7 years ago)
From
Magnus Axelsson at Stockholm U. <magaxe@kth.se>
M. Axelsson (KTH and Stockholm Univ.), D. Kocevski (NASA/MSFC), E. Bissaldi (Politecnico & INFN Bari) and M. Yassine (Univ. & INFN Trieste) report on behalf of the Fermi-LAT team:
On October 28, 2018, Fermi-LAT detected high-energy emission from GRB 181028A, which was also detected by Fermi-GBM (trigger 562428587).
The best LAT on-ground location is found to be
RA, Dec = 88.9, -22.0 (J2000)
with an error radius of 0.4 deg (90 % containment, statistical error only). This is 4.9 deg from the GBM location.
This was 60 deg from the LAT boresight at the time of the GBM trigger: 14:09:42.53 UT.
The data from the Fermi-LAT in the time interval 0-300s after the GBM trigger show a significant increase in the event rate that is spatially correlated with the trigger with very high significance. The highest-energy photon is a 1.7 GeV event which is observed 295 seconds after the GBM trigger.
The Fermi-LAT point of contact for this burst is Manal Yassine (mychbib@gmail.com<mailto:mychbib@gmail.com>).
The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden