GRB 180703B
GCN Circular 23058
Subject
GRB 180703B: CALET CAL gamma-ray analysis
Date
2018-07-30T09:44:28Z (7 years ago)
From
Takanori Sakamoto at AGU <tsakamoto@phys.aoyama.ac.jp>
K. Yoshikawa, Y. Asaoka (Waseda U), N. Cannady (LSU),
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),
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:
Using the CALET CALorimeter (CAL) data, we report GeV gamma-ray search
analysis associated to GRB 180703B (Racusin et al. GCN Circ. 22884;
Takahashi et al. GCN Circ. 22888; Poolakkil and Meegan GCN Circ. 22897;
Hurley et al. GCN Circ. 22908; Frederiks et al. GCN Circ. 22914).
The CAL was operating in low energy trigger mode at the trigger time of
the CALET Gamma-ray Burst Monitor (CGBM). We have searched for
gamma-ray events in the 1-10 GeV band from -60 sec to +60 sec from
the CGBM trigger time using the Fermi-LAT position (Racusin et al.
GCN Circ. 22884) and found no candidates. The 90% upper limit of CAL is
1.5e-6 erg/cm2/s (1-10 GeV) assuming a power-law spectrum of a photon
index of -2.
All the quoted values are preliminary.
GCN Circular 22932
Subject
GRB 180703B: further analysis of CGBM data
Date
2018-07-09T14:07:10Z (7 years ago)
From
Takanori Sakamoto at AGU <tsakamoto@phys.aoyama.ac.jp>
V. Pal'shin, Y. Kawakubo, A. Yoshida, T. Sakamoto, S. Sugita, 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:
Using the CALET Gamma-ray Burst Monitor (CGBM) event data
we report further analysis of the bright, short-duration, soft spectrum
GRB 180703B (Fermi-LAT detection: Racusin et al. GCN Circ. 22884;
CGBM detection: Takahashi et al. GCN Circ. 22888;
Fermi-GBM detection: Poolakkil and Meegan GCN Circ. 22897;
IPN localization: Hurley et al. GCN Circ. 22908;
Konus-Wind observation: Frederiks et al. GCN Circ. 22914).
Using a 16-ms binned light curve of the sum of HXM1 and HXM2 detectors,
the estimated spectral lag for the 25-50 keV to 100-300 keV bands is
43 �� 30 ms (68% CL). This value is more consistent with lags of long rather
than short GRBs.
We also obtained more precise estimates of T90 and T50 using the SGM 16-ms lc:
1.44 s +- 0.10 s and 0.34 +- 0.06 sec (40-1000 keV), respectively.
The time-averaged spectrum of the burst (measured by the SGM from T0+0.032 sec
to T0+1.856 sec, where T0=22:46:51.183 UTC) is best fit in the 30-1000 keV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.83(-0.32, +0.36) and Ep = 143(-13, +15) keV (chi2 = 62/59 dof).
The resulting fluence in this energy range is 5.98(-0.43, +0.46)x10^-6 erg/cm2.
The quoted errors are at 90% CL.
All the quoted values are preliminary.
GCN Circular 22914
Subject
Konus-Wind observation of GRB 180703B
Date
2018-07-06T11:56:57Z (7 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
D. Frederiks, S. Golenetskii, R.Aptekar, A. Kozlova,
A.Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
GRB 180703B (IPN Triangulation: Hurley et al., GCN 22908;
Fermi-LAT detection: Racusin et al., GCN 22884;
Fermi-GBM detection: Poolakkil & Meegan, GCN 22897)
triggered Konus-Wind at T0=82008.633 s UT (22:46:48.633)
The burst light curve shows two prominent peaks,
with a total duration of ~2.0 s.
The emission in the main peak is seen up to ~2 MeV.
As observed by Konus-Wind, the burst had a fluence of
(6.4 �� 0.4)x10^-6 erg/cm2 and a 64-ms peak energy flux,
measured from T0+1.088, of (1.60 �� 0.09)x10^-5 erg/cm2
(both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum (measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 2 MeV range by a cutoff power-law
(CPL) function with the following model parameters:
the photon index alpha = -0.74(-0.18,+0.19),
and the peak energy Ep = 131(-9,+11) keV,
chi2 = 55/57 dof.
Fitting this spectrum with the GRB (Band) function yields
the same alpha and Ep, and only an upper limit on beta (<-3.3).
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180703_T82008/
All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.
GCN Circular 22908
Subject
IPN Triangulation of GRB 180703B
Date
2018-07-06T05:14:31Z (7 years ago)
From
Anna Kozlova at Ioffe Institute <ann_kozlova@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,
A. Kozlova, S. Golenetskii, R. Aptekar, D. Frederiks, D. Svinkin,
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,
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 short duration GRB 180703B
(Fermi-LAT detection: Racusin et al., GCN Circ. 22884;
CGBM detection: Takahasi et al., GCN Circ. 22888;
Fermi-GBM detection: Poolakkil and Meegan, GCN Circ. 22897)
was detected by Fermi (GBM trigger 552350816), Konus-Wind,
INTEGRAL (SPI-ACS), Mars-Odyssey (HEND), CALET (CGBM),
and Swift (BAT), at about 82009 s UT (22:46:49).
The burst was outside the coded field of view of the BAT.
We have triangulated it to a Konus-HEND annulus centered at
RA(2000)=132.436 deg (08h 49m 45s) Dec(2000)=+22.998 deg (+22d 59' 54"),
whose radius is 62.605 +/- 0.326 deg (3 sigma).
The LAT position reported by Racusin et al. (GCN Circ. 22884)
is consistent with the annulus. The annulus combined with
the LAT (90 % containment, statistical-only) error circle
gives the following error box:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
97.0594 -29.7187
Corners:
96.9223 -29.8774
97.2925 -30.1165
97.1962 -29.5599
96.5548 -29.6361
---------------------------------------------
The error box area is 894.7 sq. arcmin
(a factor of 2 smaller than that of the LAT error circle).
This box may be improved.
A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB180703_T82008/IPN
GCN Circular 22897
Subject
GRB 180703B: Fermi GBM detection
Date
2018-07-04T17:00:32Z (7 years ago)
From
Suraj Poolakkil at UAH <sp0076@uah.edu>
S.Poolakkil and C. Meegan (both UAH) report on
behalf of the Fermi GBM Team:
"At 22:46:51.32 UT on 03 July 2018, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 180703B (trigger 552350816/ 180703949),
which was also detected by the Fermi LAT (Racusin et al. 2018, GCN 22884).
The GBM on-ground location is consistent with the LAT position.
The angle from the Fermi LAT boresight
at the GBM trigger time is 31 degrees.
The GBM light curve shows two peaks
with a duration (T90) of about 1.6 s (50-300 keV).
The time-averaged spectrum from T0-0.1 s to T0+2.4 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.79 +/- 0.03 and
the cutoff energy, parameterized as Epeak, is 138 +/- 3 keV.
The event fluence (10-1000 keV) in this time interval is
(8.281 +/- 0.119)E-06 erg/cm^2. The 64-ms peak photon flux measured
starting from T0+1.21 s in the 10-1000 keV band
is 103.9 +/- 2.92 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
GCN Circular 22888
Subject
GRB 180703B: CALET Gamma-Ray Burst Monitor detection
Date
2018-07-04T09:24:53Z (7 years ago)
From
Valentin Pal'shin at AGU <val@phys.aoyama.ac.jp>
I. Takahashi (IPMU), 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),
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 Fermi-LAT GRB 180703B (Racusin et al. GCN Circ. 22884) triggered
the CALET Gamma-ray Burst Monitor (CGBM) at 22:46:51.183 UTC on 3 July 2018.
The burst signal was seen by all CGBM detectors.
The burst light curve shows two short pulses which start at T+0.1 sec,
peaks at T+1.4 sec and ends at T+2.1 sec. The T90 and the T50 durations
measured by the SGM data are 1.4 +- 0.2 sec and 0.4 +- 0.1 sec (40-1000 keV),
respectively.
Despite its very high brightness the burst spectrum is soft with almost
no emission seen in the CGBM data above ~500 keV. So, this is a very bright,
short, and soft GRB.
The follow-up observations of this interesting event is highly encouraged.
The ground processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1214693124/
The CALET data used in this analysis are provided by the Waseda CALET Operation
Center located at the Waseda University.
GCN Circular 22884
Subject
GRB 180703B: Fermi-LAT detection
Date
2018-07-04T02:35:47Z (7 years ago)
From
Judith Racusin at GSFC <judith.racusin@nasa.gov>
J. L. Racusin (NASA/GSFC), M. Crnogor��evi�� (UMD), A. Barker (George Washington),
G. Vianello (Stanford), M. Axelsson (KTH and Stockholm University) report on behalf
of the Fermi-LAT team:
At 22:46:51.32 UTC on July 03, 2018 Fermi-LAT detected high-energy emission from
GRB 180703B, which was also detected by Fermi-GBM (trigger 552350816 / 180703949).
The best LAT on-ground location is found to be
RA, Dec = 96.92, -29.88 (J2000)
with an error radius of 0.4 deg (90% containment, statistical error only).
This was 30 deg from the LAT boresight at the time of the trigger.
The data from the Fermi-LAT show a significant increase in the event rate that is spatially
and temporally correlated with the trigger with high significance.
The highest-energy photon is a ~1 GeV event which is observed 35 seconds after the GBM
trigger.
A Swift ToO has been requested for this burst.
The Fermi-LAT point of contact for this burst is Judith Racusin (judith.racusin@nasa.gov).
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.