GRB 250627A
GCN Circular 40871
Subject
GRB 250627A: SVOM/GRM detection of a short burst
Date
2025-06-29T14:35:58Z (a month ago)
From
Chenwei Wang at IHEP <cwwang@ihep.ac.cn>
Via
Web form
SVOM/GRM team: Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Jean-Luc Atteia (IRAP)
Report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by a hard short burst GRB 250627A (SVOM trigger reference: sb25062711) at 2025-06-27T16:46:23 UTC (T0).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a single pulse with a T90 of 0.9 +0.2/-0.4 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb250627A.png
In addition, ECLAIRs was collecting data at the time of this burst and also detected this burst in the energy range of above 50 keV, although this burst is outside ECLAIRs FOV.
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS.
The SVOM point of contact for this burst is: Chen-Wei Wang (IHEP)(cwwang@ihep.ac.cn)
GCN Circular 40872
Subject
GRB 250627A: Insight-HXMT detection
Date
2025-06-29T15:49:05Z (a month ago)
From
Chenwei Wang at IHEP <cwwang@ihep.ac.cn>
Via
Web form
Chen-Wei Wang, Shao-Lin Xiong, and Chao Zheng report on behalf of the Insight-HXMT team:
At 2025-06-27T16:46:23 (T0), Insight-HXMT/HE detected the short burst GRB 250627A, which is also detected by SVOM/GRM (Wang et al., GCN #40871).
The Insight-HXMT/HE light curve mainly consists of a single pulse with a T90 of 0.9 +0.1/-0.2 s.
The 1s peak rate, measured from T0+0.175 s, is 7839 cnts/sec.
The total counts from this burst is 8292 counts.
The HXMT/HE light curve can be found here:
https://www.bursthub.cn//admin/static/hxmtgrb250627A.png
All measurements above are made with the CsI detectors operating in the regular mode with the energy range of about 60-900 keV (deposited 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 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.
GCN Circular 40888
Subject
IPN triangulation of GRB 250627A (short)
Date
2025-07-02T16:13:38Z (25 days ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
Via
Web form
A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the HEND/Mars Odyssey team,
A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin,
and T. Cline on behalf of the Konus-Wind team,
E. Burns on behalf of the IPN,
Y. Zhang, C. Wang, S. Xiong, J. Wei, and B. Cordier
on behalf of the SVOM-GRM team,
and
W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr,
and A.S. Gardner on on behalf of the GRS-Odyssey GRB team,
report:
The short-duration GRB 250627A
(SVOM-GRM detection: Wang et al., GCN 40871;
Insight-HXMT detection: Wang et al., GCN 40872)
was detected by SVOM (GRM), Insight-HXMT, Konus-Wind,
and Mars-Odyssey (HEND) at about 60378 s UT (16:46:18).
We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
90.764 (06h 03m 03s) +10.097 (+10d 05' 48")
Corners:
90.676 (06h 02m 42s) +10.618 (+10d 37' 04")
90.803 (06h 03m 13s) +9.585 ( +9d 35' 07")
90.855 (06h 03m 25s) +9.577 ( +9d 34' 37")
90.727 (06h 02m 55s) +10.609 (+10d 36' 32")
---------------------------------------------
The error box area is 185 sq. arcmin, and its maximum
dimension is 1.1 deg (the minimum one is 2.4 arcmin).
The Sun distance was 14 deg.
This localization may be improved.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB250627_T60377/IPN
The HEALPix triangulation map is the multi-order HEALPix in units of
probability density.
The Konus-Wind time history and spectrum will be given
in a forthcoming GCN Circular.
GCN Circular 40889
Subject
Konus-Wind detection of GRB 250627A
Date
2025-07-02T16:17:20Z (25 days ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
Via
Web form
A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
The short-duration GRB 250627A
(SVOM-GRM detection: Wang et al., GCN 40871;
Insight-HXMT detection: Wang et al., GCN 40872;
IPN triangulation: Kozyrev et al., GCN 40888)
triggered Konus-Wind at T0=60377.861 s UT (16:46:17.861).
The burst light curve shows a multipeaked structure
which starts at ~T0-0.3 s and has a total duration of ~1.1 s.
The emission is seen up to ~10 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB250627_T60377/
As observed by Konus-Wind, the burst
had a fluence of 9.65(-1.16,+1.29)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0+0.420 s,
of 2.60(-0.49,+0.52)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+8.448 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 = -0.31(-0.21,+0.25)
and Ep = 874(-128,+160) keV (chi2 = 73/76 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 = 73/75 dof).
All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.