GCN Circular 38103

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

The likely short GRB 241105A (Fermi GBM team, GCN 38085
Not found
 
 
)
triggered Konus-Wind (KW) at T0=57966.516 s UT (16:06:06.516).

The burst light curve shows a short initial pulse,
which starts at ~T0-0.5 s, peaks at ~T0, and has a total duration
of ~1.5 s, which was followed by a weaker extended emission,
visible in KW up to ~T0+60 s.
The emission is seen up to ~4 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB241105_T57966/

As observed by Konus-Wind, the burst had
a fluence of (2.01 ± 0.47)x10^-5 erg/cm^2 and
a 64-ms peak energy flux, measured from T0 - 0.064 s,
of (2.37 ± 0.30)x10^-6 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+57.640 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 = -0.69 (-0.37,+0.67),
the high energy photon index beta = -1.76 (-0.55,+0.21),
the peak energy Ep = 374 (-165,+437) keV,
chi2 = 98/97 dof.

The spectrum of the initial pulse alone (measured from T0-0.512 s to T0+0.960 s)
can be described by a power law with exponential cutoff (CPL) model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.90(-0.15,+0.15) and Ep = 417(-82,+111) keV.

Assuming the redshift z=2.702 (Izzo et al., GCN 38097
Not found
 
 
)
and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315,
and Omega_Lambda = 0.685 (Planck Collaboration, 2014),
we estimate the burst isotropic energy release E_iso to (3.42 ± 0.80)x10^53 erg,
the isotropic peak luminosity L_iso to (1.49 ± 0.18)x10^53 erg/s,
the rest-frame peak energy of the time-integrated spectrum Ep,i,z to ~1380 keV,
and the rest-frame peak energy at the peak of the emission Ep,p,z to ~1540 keV.
With the obtained estimates, GRB 241105A fits 68% prediction bands for
both 'Amati' and 'Yonetoku' relations derived for the sample of >300 long
KW GRBs with known redshifts (Tsvetkova et al., 2017; Tsvetkova et al., 2021),
see http://www.ioffe.ru/LEA/GRBs/GRB241105_T57966/GRB241105A_rest_frame.pdf

All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.