GCN Circular 39021
Subject
GRB 250121A: CALET Gamma-Ray Burst Monitor detection
Date
2025-01-24T14:43:22Z (17 days ago)
From
Yuta Kawakubo at Aoyama Gakuin University <kawakubo@phys.aoyama.ac.jp>
Via
Web form
T. Sakamoto, A. Yoshida, 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), M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:
The long GRB 250121A (Fermi GBM Final Real-time Localization: Fermi GBM team, GCN Circ. 39006;
Fermi-LAT detection: Holzmann Airasca et al., GCN Circ. 39010;
INTEGRAL/SPI-ACS detection: Barria et al., GCN Circ. 39011;
Fermi GBM Observation: Godwin et al., GCN Circ. 39018;
) was detected in the ground analysis of the CALET Gamma-ray
Burst Monitor (CGBM) data around 23:36:05.78 on 21 January 2025 (referenced
to the Fermi-GBM Observation: GCN Circ. 39018).
(https://cgbm.calet.jp/cgbm_trigger/flight/1421537655/index.html).
The burst signal was seen by only the SGM detector.
The burst light curve shows a double-peaked structure that starts
at T+0.1 sec, peaks at T+0.7 sec, and ends at T+5.4 sec.
The T90 and T50 durations measured by the SGM data are 4.7 +/- 0.2 sec
and 2.6 +/- 0.4 sec (40-1000 keV), respectively.
The ground-processed light curve is available at
https://cgbm.calet.jp/cgbm_trigger/ground/1421537655/
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.