TITLE:   GCN CIRCULAR
NUMBER:  41762
SUBJECT: GRB 250907A: CALET Gamma-Ray Burst Monitor detection
DATE:    25/09/09 07:19:26 GMT
FROM:    Yuta Kawakubo at Aoyama Gakuin University <kawakubo@phys.aoyama.ac.jp>

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

The long GRB 250907A (GECAM-B detection: Wang et al., GCN Circ. 41749)
triggered the CALET Gamma-ray Burst Monitor (CGBM) at 22:00:54.59 UTC on 7 September 2025
(https://cgbm.calet.jp/cgbm_trigger/flight/1441317257/index.html).

The burst signal was seen by all CGBM detectors.  Because of a problem with the ground 
alert processing script, the GCN notice was not distributed automatically for this event.

The burst light curve shows a single pulse that starts
at T-0.9 sec, peaks at T+0.4 sec, and ends at T+5.9 sec.
The T90 and T50 durations measured by the SGM data are 6.0 +/- 0.6 sec
and 3.0 +/- 0.2 sec (40-1000 keV), respectively.

The ground-processed light curve is available at

https://cgbm.calet.jp/cgbm_trigger/ground/1441317257/

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