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GCN Circular 35697

Subject
GRB 240205B: CALET Gamma-Ray Burst Monitor detection
Date
2024-02-07T01:32:14Z (22 days ago)
From
Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>
Via
Web form
T. Sakamoto, A. Yoshida, S. Sugita (AGU), Y. Kawakubo (LSU),
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 240205B (Fermi GBM Final Real-time Localization: 
Fermi GBM team, GCN Circ. 35682; Swift detection: Moss et al.,
GCN Circ. 35683; INTEGRAL SPI-ACS Trigger #10513; GECAM 
detection: Zhang et al., GCN Circ. 35689;  Fermi GBM Observation:
Fletcher et al., GCN Circ. 35693) triggered the CALET Gamma-ray 
Burst Monitor (CGBM) at 22:13:45.98 UTC on 5 February 2024
(http://cgbm.calet.jp/cgbm_trigger/flight/1391206207/).
The burst signal was seen by only the SGM detector.

Based on the GRB position reported by Swift-BAT (referenced to
GCN Circ. 35683), the angle from the SGM bore-sight is 106 
degrees, and the direction was blocked by the structures of the 
International Space Station.  Although the observed light curve was
affected by the structures, SGM detected the brightest peak which
was observed by Fermi-GBM, INTEGRAL SPI-ACS, and GECAM.

The burst light curve shows a single pulse that starts at T+0.0 sec, 
peaks at T+0.4 sec, and ends at T+0.9 sec. The T90 and T50 durations 
measured by the SGM data are 0.7 +/- 0.3 sec and 0.2 +/- 0.1 sec 
(40-1000 keV), respectively.

The ground-processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1391206207/index.html

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