GCN Circular 21705

M. L. Cherry (LSU), A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama,
Y. Yamada, A. Tezuka, S. Matsukawa (AGU), K. Yamaoka (Nagoya U),
S. Nakahira (RIKEN), I. Takahashi (IPMU), Y. Asaoka, S. Ozawa,
S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR),
S. Ricciarini (U of Florence), A. V. Penacchioni, P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The long-duration GRB 170820A (Konus-Wind trigger time on 11:12:06.755 UT)
triggered the CALET Gamma-ray Burst Monitor (CGBM) at 11:12:05.10 on
20 August 2017.  The burst signal was seen by the all CGBM instruments.

The light curve of the SGM shows a single peak.  The emission starts at
T+1 sec, peaks at T+4.5 sec and ends at T+9 sec.  There is a hint of the
peaked emission at T+8 sec.  The T90 duration measured by the
SGM data is 4.1 +- 0.5 sec (40-1000 keV).

The light curve is available at

http://cgbm.calet.jp/cgbm_trigger/flight/1187262128/

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

[GCN OPS NOTE(25aug17): Per author's request, the URL was corrected
from 1187301799 to 1187262128.]