[vsnet-grb-info 28300] Konus-Wind detection of GRB 210706A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30403
SUBJECT: Konus-Wind detection of GRB 210706A
DATE:    21/07/07 13:05:45 GMT
FROM:    Anna Ridnaia at Ioffe Institute  <ridnaia at mail.ioffe.ru>

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

The long-duration GRB 210706A
(Fermi GBM trigger 647252274;
Swift/BAT-GUANO detection: Tohuvavohu et al., GCN 30393)
triggered Konus-Wind at T0=29875.487 s UT (08:17:55.487).

The burst light curve shows a multipeaked structure
started at ~T0-2.7 s with a total duration of ~8.9 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/GRB210706_T29875/

As observed by Konus-Wind, the burst
had a fluence of 5.39(-0.66,+0.90)x10^-6 erg/cm2,
and a 64-ms peak flux, measured from T0+1.040 s,
of 2.73(-0.92,+0.99)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 - 4 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -1.11(-0.26,+0.30)
and Ep = 263(-59,+112) keV (chi2 = 65/71 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.3
(chi2 = 65/70 dof).

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