GCN Circular 36659

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

The very bright, long-duration GRB 240607A
(Fermi-GBM detection: The Fermi GBM team, GCN 36634
Not found
 
 
;
Dalessi, GCN 36637
Not found
 
 
; Dalessi and Meegan, GCN 36641
Not found
 
 
;
BALROG localization: Preis et al., GCN 36635
Not found
 
 
;
AstroSat-CZTI detection: Waratkar et al., GCN 36638
Not found
 
 
;
IPN triangulation: Kozyrev at al., GCN 36650
Not found
 
 
)
triggered Konus-Wind at T0=39674.62 s UT (11:01:14.620).

The burst light curve shows a multipeaked structure
which starts at ~T0-0.2 s and has a total duration of ~24.7 s.
The emission is seen up to ~6 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB240607_T39674/

As observed by Konus-Wind, the burst
had a fluence of 1.03(-0.06,+0.05)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+10.960 s,
of 3.02(-0.33,+0.34)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+29.440 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 = -0.94(-0.05,+0.05),
the high energy photon index beta = -2.92(-0.42,+0.22),
the peak energy Ep = 248(-13,+13) keV
(chi2 = 111/98 dof).

The spectrum near the maximum count rate
(measured from T0+10.752 to T0+11.264 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 = -0.21(-0.18,+0.19),
the high energy photon index beta = -2.77(-0.37,+0.20),
the peak energy Ep = 249(-24,+31) keV
(chi2 = 54/46 dof).

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