GRB 210602A
GCN Circular 30113
Subject
GRB 210602A: MAXI/GSC detection
Date
2021-06-02T12:44:38Z (4 years ago)
From
Motoko Serino at Aoyama Gakuin U. <serino@phys.aoyama.ac.jp>
M. Serino, S. Sugita (AGU),
H. Negoro, M. Nakajima, K. Kobayashi, K. Asakura, K. Seino (Nihon U.),
T. Mihara, T. Tamagawa, M. Matsuoka (RIKEN),
T. Sakamoto, K. Komachi, A. Yoshida (AGU),
Y. Tsuboi, W. Iwakiri, H. Kawai, Y. Okamoto, S. Kitakoga (Chuo U.),
M. Shidatsu (Ehime U.),
N. Kawai, M. Niwano, R. Hosokawa (Tokyo Tech),
S. Nakahira, Y. Sugawara, S. Ueno, H. Tomida, M. Ishikawa, M. Tominaga, T. Nagatsuka (JAXA),
Y. Ueda, S. Yamada, S. Ogawa, K. Setoguchi, T. Yoshitake, Y. Goto, R. Uematsu (Kyoto U.),
H. Tsunemi (Osaka U.),
M. Yamauchi, Y. Nonaka, T. Sato, R. Hatsuda, R. Fukuoka (Miyazaki U.), T. Kawamuro (UDP/NAOJ),
K. Yamaoka (Nagoya U.),
Y. Kawakubo (LSU),
M. Sugizaki (NAOC)
report on behalf of the MAXI team:
The MAXI/GSC nova alert system triggered a bright uncatalogued
X-ray transient source at 12:04:02 UT on 2021 June 2.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (44.630 deg, -2.672 deg) = (02 58 31, -02 40 19) (J2000)
with a statistical 90% C.L. elliptical error region
with long and short radii of 0.17 deg and 0.16 deg, respectively.
The roll angle of long axis from the north direction is 107.0 deg counterclockwise.
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 393 +- 52 mCrab
(4.0-10.0keV, 1 sigma error).
Without assumptions on the source constancy, we obtain a rectangular error
box for the transient source with the following corners:
(R.A., Dec) = (43.754, -3.549) deg = (02 55 00, -03 32 56) (J2000)
(R.A., Dec) = (44.013, -3.735) deg = (02 56 03, -03 44 05) (J2000)
(R.A., Dec) = (45.446, -1.751) deg = (03 01 47, -01 45 03) (J2000)
(R.A., Dec) = (45.187, -1.565) deg = (03 00 44, -01 33 53) (J2000)
There was no significant excess flux in the previous transit at 10:31 UT
with an upper limit of 20 mCrab.
GCN Circular 30117
Subject
GRB 210602A: CALET Gamma-Ray Burst Monitor detection
Date
2021-06-03T07:04:45Z (4 years ago)
From
Valentin Pal'shin at AGU <val@phys.aoyama.ac.jp>
V. Pal'shin, A. Yoshida, T. Sakamoto, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC),
M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:
The bright GRB 210602A (MAXI/GSC detection: Serino et al., GCN Circ. 30113)
triggered the CALET Gamma-ray Burst Monitor (CGBM) at 12:04:01.493 UTC
on 2 June 2021
(http://cgbm.calet.jp/cgbm_trigger/flight/1306670489/index.html).
The burst signal was seen by all CGBM detectors.
The burst light curve shows a single pulse which starts at T+0.5 sec,
peaks at T+1.4 sec, and ends at T+3.0 sec. The T90 and T50 durations
measured by the SGM data are 1.9 +- 0.3 sec and 0.5 +- 0.1 sec (40-1000
keV), respectively.
The ground processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1306670489/
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at the Waseda University.
GCN Circular 30145
Subject
Konus-Wind detection of GRB 210602A
Date
2021-06-07T15:08:45Z (4 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
D. Frederiks, S. Golenetskii, A.Lysenko, D. Svinkin,
A. Ridnaya, A. Tsvetkova, M. Ulanov, and T. Cline, report:
The bright GRB 210602A (MAXI/GSC detection: Serino et al., GCN 30113;
CALET Gamma-Ray Burst Monitor detection: Pal'shin et al., GCN 30117)
triggered Konus-Wind (KW) at T0=43439.748 s UT (12:03:59.748).
The burst light curve shows a single pulse which starts at ~T0-0.5 s,
peaks at ~T0+0.512 s, and has the total duration of ~3.1 s (T100, 20-1500 keV).
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/GRB210602_T43439/
As observed by Konus-Wind, the burst had
a fluence of (6.3 �� 0.6)x10^-6 erg/cm^2 and
a 64-ms peak energy flux, measured from T0+0.384,
of (9.5 �� 1.0)x10^-6 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst (measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 15 MeV range
by a power law with exponential cutoff (CPL) model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -1.25(-0.23,+0.26) and Ep = 188(-33,+58) keV (chi2 = 75/97 dof).
Fitting this spectrum by a Band function yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.2 (chi2 = 75/96 dof).
All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.