TITLE: GCN CIRCULAR NUMBER: 27301 SUBJECT: GRB 200303A: CALET Gamma-Ray Burst Monitor detection DATE: 20/03/03 09:23:42 GMT FROM: Valentin Pal'shin at AGU Y. Asaoka (Waseda U), A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU), Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), S. Torii (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 200303A (Fermi GBM Final Real-time Localization: Fermi GBM Team, GCN Circ. 27294; Swift detection: Cenko et al., GCN Circ. 27297; https://gcn.gsfc.nasa.gov/other/200303A.gcn3) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 02:34:20.728 UTC on 3 March 2020. The burst signal was seen by all CGBM detectors. The burst light curve shows a multi-peaked structure which starts at T+2.3 sec, peaks at T+39.4 sec, and ends at T+88.8 sec. The T90 and T50 durations measured by the SGM data are 68.9 +- 12.8 sec and 28.9 +- 3.3 sec (40-1000 keV), respectively. The ground processed light curve is available at http://cgbm.calet.jp/cgbm_trigger/ground/1267237773/ The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University.