TITLE: GCN CIRCULAR NUMBER: 39016 SUBJECT: Konus-Wind detection of GRB 250119B DATE: 25/01/23 15:22:17 GMT FROM: Anna Ridnaia at Ioffe Institute ridnaia@mail.ioffe.ru

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 250119B (Fermi-GBM detection: Fermi GBM team, GCN 38979; Preis et al., GCN 38980; Pathak et al., GCN 39003; INTEGRAL/SPI-ACS detection: Barria et al., GCN 38997; Swift-BAT/GUANO detection: Ronchini et al., 39007 IPN triangulation: Kozyrev et al., GCN 39015) triggered Konus-Wind at T0=30434.631 s UT (08:27:14.631).

The burst light curve shows two separated multipeaked emission episodes. The first episode starts at ~T0-18.6 s and has a total duration of ~162 s, the second starts at ~T0+233 s and lasts up to ~T0+274 s. The emission is seen up to ~3 MeV.

The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB250119_T30434/

As observed by Konus-Wind, the burst had a fluence of 1.36(-0.16,+0.16)x10^-4 erg/cm2, and a 64-ms peak flux, measured from T0+31.440 s, of 9.43(-1.10,+1.11)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst (measured from T0 to T0+273.664 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 = -1.02(-0.08,+0.09), the high energy photon index beta = -2.37(-0.35,+0.19), the peak energy Ep = 332(-36,+43) keV (chi2 = 95/96 dof).

The spectrum near the maximum count rate (measured from T0+29.184 to T0+36.096 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 = -0.64(-0.08,+0.09), the high energy photon index beta = -2.43(-0.17,+0.12), the peak energy Ep = 297(-20,+23) keV (chi2 = 85/79 dof).

All the quoted errors are at the 68% confidence level. All the quoted values are preliminary.

View this GCN Circular online at https://gcn.nasa.gov/circulars/39016. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...