TITLE: GCN CIRCULAR NUMBER: 39152 SUBJECT: Konus-Wind detection of GRB 250201A DATE: 25/02/05 16:18:27 GMT FROM: Dmitry Frederiks at Ioffe Institute fred@mail.ioffe.ru
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.
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