TITLE:   GCN CIRCULAR
NUMBER:  32128
SUBJECT: GRB 220521B: CALET Gamma-Ray Burst Monitor detection
DATE:    22/05/26 23:44:02 GMT
FROM:    Yuta Kawakubo at Louisiana State U./CALET  <kawakubo1@lsu.edu>

T. Sakamoto, A. Yoshida, S. Sugita (AGU), Y. Kawakubo (LSU), 
K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), Y. Asaoka (ICRR),
S. Torii, Y. Akaike, K. Kobayashi (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC),
M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The long GRB 220521B (Konus-Wind detection: A.Ridnaia et al., GCN Circ 32106; 
IPN triangulation: Kozyrev et al., GCN Circ 32104) triggered the CALET Gamma-ray
Burst Monitor (CGBM) at 15:03:34.307 UTC on 21 May 2022
(http://cgbm.calet.jp/cgbm_trigger/flight/1337180454/index.html).
The burst signal was seen by only SGM detector.
No real-time CGBM GCN notice was distributed about this trigger because
the real-time communication from the ISS was off (loss of signal).

The burst light curve shows a single pulse which starts
at T-0.5 sec, peaks at T+0.8 sec, and ends at T+1.5 sec.
The T90 and T50 durations measured by the SGM data are 1.6 +/- 0.3 sec
and 0.8 +/- 0.2 sec (40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1337180454/

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