GCN Circular 39152
Subject
Konus-Wind detection of GRB 250201A
Date
2025-02-05T16:18:27Z (5 days ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
Via
email
D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
The long GRB 250201A (Fermi-GBM detection: Fermi GBM team, GCN 39112;
BALROG localization: Preis & Greiner, GCN 39113;
INTEGRAL SPI/ACS detection: Barria et al., GCN 39117;
IPN triangulation: Kozyrev et al., GCN 39151)
triggered Konus-Wind (KW) at T0=35989.814 s UT (09:59:49.814).
The burst light curve shows a double-peaked emission pulse
with the total duration of ~21 s.
The emission is seen up to ~8 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB250201_T35989/
As observed by Konus-Wind, the burst had
a fluence of (1.21 ± 0.08)x10^-5 erg/cm^2 and
a 64-ms peak energy flux, measured from T0 + 12.160 s,
of (2.97 ± 0.34)x10^-6 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum (measured from T0 to T0+16.640 s)
is best fit in the 20 keV - 15 MeV range
by a GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.72 (-0.12,+0.13),
the high energy photon index beta = -3.07 (-0.54,+0.27),
the peak energy Ep = 134 (-7,+8) keV,
chi2 = 118/97 dof.
The spectrum near the peak count rate (measured from T0+8.448 s to T0+16.640 s)
is best fit in the 20 keV - 15 MeV range
by a GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.76 (-0.11,+0.13),
the high energy photon index beta = -2.95 (-0.34,+0.23),
the peak energy Ep = 138 (-8,+8) keV,
chi2 = 94/78 dof.
All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.