GCN Circular 36830
Subject
Konus-Wind detection of GRB 240627A
Event
Date
2024-07-05T15:19:45Z (a year 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 long-duration GRB 240627A
(AstroSat-CZTI detection: Joshi et al., GCN 36776;
NuSTAR anti-coincidence shields detection: Grefenstette, GCN 36778;
CALET-CGBM detection: Kobayashi et al., GCN 36798;
IPN triangulation: Kozyrev et al., GCN 36814;)
triggered Konus-Wind at T0=86332.21 s UT (23:58:52.210).
The burst light curve shows a multipeaked structure
which starts at ~T0-45.2 s and has a total duration of ~91.0 s.
The emission is seen up to ~4 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB240627_T86332/
As observed by Konus-Wind, the burst
had a fluence of 5.22(-0.54,+0.57)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+6.016 s,
of 1.27(-0.23,+0.23)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+47.616 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.31(-0.07,+0.09),
the high energy photon index beta = -2.47(-0.39,+0.20),
the peak energy Ep = 191(-23,+25) keV
(chi2 = 110/87 dof).
The spectrum near the maximum count rate
(measured from T0+5.376 to T0+7.168 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.06(-0.10,+0.11),
the high energy photon index beta = -2.49(-0.63,+0.26),
the peak energy Ep = 314(-54,+61) keV
(chi2 = 49/55 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.