GRB 190404B

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

The long GRB 190404B which triggered MAXI/GSC at 12:24:20 UT
(MAXI/GSC detection: Nakajima et al., GCN 24048
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CALET Gamma-Ray Burst Monitor detection: Nakahira et al., GCN 24055
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was detected by Konus-Wind in the waiting mode.

The burst light curve shows a single multi-peaked emission episode
started at ~T0(MAXI)-7.4 s with a total�� duration of ~85.4 s.

As observed by Konus-Wind, the burst had a fluence of
5.57(-1.00,+1.34)x10^-6 erg/cm2 and a 2.944-s peak flux,
measured from ~T0(MAXI)+51.5 s, of 1.09(-0.20,+0.26)x10^-7 erg/cm2/s
(both in the 20 - 1200 keV energy range).

Fitting the K-W 3-channel time-integrated spectrum
(from ~T0(MAXI)-7.4 s to ~T0(MAXI)+78.0 s) in the 20 keV - 1.2 MeV range
by a power law with exponential cutoff model
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) yields
alpha = -1.64(-0.36,+3.80),
and Ep =80(-39,+33) keV.

All the quoted errors are estimated at the 1 sigma confidence level.
All the presented results are preliminary.

The K-W light curve of this burst is available at
http://www.ioffe.rssi.ru/LEA/GRBs/GRB190404B/

S. Nakahira (RIKEN),
A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), I. Takahashi (IPMU),
Y. Asaoka, S. Ozawa, S. Torii (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U),
W. Ishizaki (ICRR), M. L. Cherry (LSU),
S. Ricciarini (U of Florence),
A. V. Penacchioni, P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The long GRB 190404B (MAXI/GSC detection: Nakajima et al., GCN Circ. 24048
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was detected in ground analysis of the CALET Gamma-ray Burst Monitor (CGBM)
data near the MAXI trigger time at T0=12:24:20 UTC on 4 April 2019.
The burst signal was seen by all CGBM detectors.

The burst light curve shows a single multi-peaked emission episode
which starts at T-15.1 sec and ends at T+80.4 sec.
The T90 and the T50 durations measured by the SGM data are
87.5 +- 18.8 sec and 47.6 +- 17.5 sec (40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1238415870/

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at the Waseda University.

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a series of observations, tiled on the sky, of the
MAXI GRB 190404B. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00079

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the MAXI event is high: any X-ray source
considered to be a probable afterglow candidate will be reported via a GCN Circular
after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

This circular is an official product of the Swift-XRT team.