GCN Circular 37079
Subject
Konus-Wind detection of GRB 240802A (EP240802a)
Date
2024-08-06T17:04:23Z (10 months ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
Via
legacy email
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 GRB 240802A (AstroSat CZTI detection: Waratkar et al., GCN 37018;
SVOM/GRM observation: Wang et al., GCN 37022;
IPN triangulation: Svinkin et al., GCN 37026; Kozyrev et al., GCN 37078),
associated with the fast X-ray transient EP240802a (Wang et al., GCN 37019;
Aryan et al., GCN 37021; Svinkin et al., GCN 37026; Kozyrev et al., GCN 37078),
triggered Konus-Wind (KW) at T0=38048.482 s UT (10:34:08.482).
The burst light curve shows a multi-peaked emission pulse,
which starts at ~T0-13 s and has the total duration of ~47 s.
Two main peaks in the light curve are located around ~T0 and ~T0+29 s,
respectively.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB240802_T38048/
As observed by Konus-Wind, the burst had the total fluence
of 1.63(-0.14,+0.15)x10^-5 erg/cm^2 and a 2.944-s peak energy flux,
measured from T0+0.032 s, of 8.21(-2.63,+3.09)x10^-6 erg/cm^2/s
(both in the 20 keV - 10 MeV energy range).
Due to telemetry errors in the KW triggered-mode spectra, the spectral analysis
was performed using the 3-channel waiting-mode count rates.
Modeling the time-integrated spectrum (measured from T0-13.161 s to T0+33.943 s)
by a power law with exponential cutoff (CPL) function dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
yields alpha = -1.38(-0.11, + 0.12) and Ep = 226(-36,+51) keV.
A CPL fit to the spectrum near the peak count rate (measured from T0-1.385 s to T0+1.559 s)
results in alpha = -1.02(-0.15,+0.17) and Ep = 273(-42,+55) keV.
All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.