GCN Circular 39590
Subject
Konus-Wind detection of GRB 250222A
Date
2025-03-04T13:35:08Z (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 250222A (SVOM-GRM detection: Wang et al., GCN 39454;
IPN triangulation: Svinkin et al., GCN 39588)
triggered Konus-Wind (KW) at T0=51862.905 s UT (14:24:22.905).
The burst light curve shows a bright, multi-peaked pulse,
with the duration of ~2.5 s, followed by a weaker, decaying emission.
The total duration of the burst is ~13 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/GRB250222_T51862/
As observed by Konus-Wind, the burst had
a fluence of (1.79 ± 0.19)x10^-5 erg/cm^2 and
a 64-ms peak energy flux, measured from T0 + 0.064 s,
of (1.53 ± 0.20)x10^-5 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 = -0.51 (-0.22,+0.26),
the high energy photon index beta = -2.28 (-0.14,+0.11),
the peak energy Ep = 173 (-21,+23) keV,
chi2 = 98/97 dof.
The spectrum near the peak count rate (measured from T0 to T0+0.256 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 = 0.40 (-0.61,+1.09),
the high energy photon index beta = -1.97 (-0.13,+0.10),
the peak energy Ep = 169 (-39,+46) keV,
chi2 = 42/43 dof.
All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.