TITLE: GCN CIRCULAR NUMBER: 33049 SUBJECT: GRB 221209A: CALET Gamma-Ray Burst Monitor detection DATE: 22/12/12 23:03:08 GMT FROM: Yuta Kawakubo at Louisiana State U./CALET Y. Kawakubo (LSU), A. Yoshida, T. Sakamoto, S. Sugita (AGU), 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 221209A (Fermi GBM Final Real-time Localization: Fermi GBM team, GCN Circ. 33031; BALROG localization: Kunzweiler et al., GCN Circ 33032; Fermi GBM observation: Bissaldi et al., GCN Circ 33034; AstroSat CZTI detection: Gopalakrishnan et al., GCN Circ 33037) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 05:50:25.591 UTC on 9 December 2022 (http://cgbm.calet.jp/cgbm_trigger/flight/1354600238/index.html). The burst signal was seen by all CGBM detectors. 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 that starts at T-2.0 sec, peaks at T+0.9 sec, and ends at T+5.0 sec. The T90 and T50 durations measured by the SGM data are 3.2 +/- 0.4 sec and 1.3 +/- 0.1 sec (40-1000 keV), respectively. The ground-processed light curve is available at http://cgbm.calet.jp/cgbm_trigger/ground/1354600238/ The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at Waseda University.