GCN Circular 37613

D. Svinkin, D. Frederiks, M. Ulanov, A. Tsvetkova,
A. Lysenko, A. Ridnaia, and T. Cline
on behalf of the Konus-Wind team, report:

The short-duration GRB 240905B
(Fermi-GBM detection: The Fermi GBM team, GCN 37389
Not found
 
 
; Dalessi et al., GCN 37436
Not found
 
 
;
AstroSat-CZTI detection: Joshi et al, GCN 37391
Not found
 
 
;
Fermi-LAT detection: Gupta et al., GCN 37418
Not found
 
 
;
IPN triangulation: Kozyrev et al., GCN 37455
Not found
 
 
;
VZLUSAT-2 detection: Dafcikova et al., GCN 37601
Not found
 
 
)
triggered Konus-Wind at T0=16038.558 s UT (04:27:18.558).

The burst light curve shows a multipeaked structure
which starts at ~T0-0.1 s and has a total duration of ~1 s.
The emission is seen up ~5 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB240905_T16038/

As observed by Konus-Wind, the burst
had a fluence of 1.68(-0.28,+0.35)x10^-5 erg/cm2,
and a 16-ms peak flux, measured from T0+0.432 s,
of 4.13(-1.05,+1.17)x10^-5 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 a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.54(-0.18,+0.21)
and Ep = 1229(-251,+357) keV (chi2 = 92/87 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.2
(chi2 = 92/86 dof).

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.