TITLE:   GCN CIRCULAR
NUMBER:  44165
SUBJECT: Konus-Wind detection of GRB 260316B
DATE:    26/03/31 13:32:29 GMT
FROM:    Valentina Panteleeva at Ioffe Institute <panteleevav228@gmail.com>

V. Panteleeva, 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-duration GRB 260316B
(Fermi-GBM detection: The Fermi GBM team, GCN 44031;
AstroSat CZTI detection: Harsha et al., GCN 44035,
SVOM/GRM detection: Wang et al., GCN 44039,
GECAM-B detection: Wang et al., GCN 44040,
CALET-GBM detection: Tamura et al., GCN 44100,
IPN triangulation: Kozyrev et al., GCN 44111)
triggered Konus-Wind at T0=61972.457 s UT (17:12:52.457).

The burst light curve shows a single pulse
which starts at ~T0-0.9 s and has a total duration of ~2.5 s.
The emission is seen up to ~5 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB260316_T61972/

As observed by Konus-Wind, the burst
had the total fluence of 2.66(-0.45,+0.56)x10^-6 erg/cm2,
and the 64-ms peak flux, measured from T0+0.230 s,
of 2.87(-0.74,+0.85)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+8.448 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 = -0.24(-0.65,+0.76),
the high energy photon index beta = -2.64(-7.36,+0.34),
the peak energy Ep = 123(-22,+58) keV
(chi2 = 64/77 dof).

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