GCN Circular 24015

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

The long-duration GRB 190324A
(Swift-BAT detection: LaPorte et al., GCN Circ. 23993
Not found
 
 
;
Fermi-GBM observation: Hui, GCN Circ. 24002
Not found
 
 
;
CALET-GBM detection: Sone et al., GCN Circ. 24006
Not found
 
 
; and
Insight-HXMT/HE detection: Luo et al., GCN Circ. 24011
Not found
 
 
)
triggered Konus-Wind at T0=81858.644 s UT (22:44:18.644).

The burst light curve shows a multipeaked structure
which starts at ~T0-3.7 s and has a total duration of ~17.3 s,
followed by a tail of softer emission seen up to ~T0+70 s.
The initial weak pulse is marginally seen at ~T0-20 s.
The emission is seen up to ~5 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB190324_T81858/

As observed by Konus-Wind, the burst
had a fluence of 2.07(-0.28,+0.31)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+1.648 s,
of 7.59(-1.80,+1.86)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+16.640 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 = -0.90(-0.18,+0.22),
the high energy photon index beta = -2.27(-0.23,+0.15),
the peak energy Ep = 146(-21,+25) keV
(chi2 = 91/97 dof).

The spectrum near the maximum count rate
(measured from T0+0.256 to T0+8.448 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 = -0.90(-0.17,+0.21),
the high energy photon index beta = -2.26(-0.22,+0.15),
the peak energy Ep = 159(-23,+27) keV
(chi2 = 77/97 dof).

Assuming the redshift z=1.1715 (Perley et al., GCN Circ. 23999
Not found
 
 
)
and a standard cosmology model with H_0 = 67.3 km/s/Mpc,
Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014),
we estimate the following rest-frame parameters:
the isotropic energy release E_iso is ~7.8x10^52 erg,
the peak luminosity L_iso is ~6.2x10^52 erg/s,
and the rest-frame peak energy of the time-integrated spectrum,
Ep,i, is ~317 keV.
With these energetics, the burst lies within the 68% prediction bands
for both 'Amati' and 'Yonetoku' relations built for the sample
of 138 long KW GRBs with known redshifts
(Tsvetkova et al., ApJ 850 161, 2017), see
http://www.ioffe.ru/LEA/GRBs/GRB190324_T81858/GRB190324A.pdf

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