TITLE: GCN CIRCULAR NUMBER: 22467 SUBJECT: GRB 180305A CALET Gamma-Ray Burst Monitor detection DATE: 18/03/11 05:23:23 GMT FROM: Takanori Sakamoto at AGU A. V. Penacchioni (U of Florence), A. Yoshida, T. Sakamoto, V. Pal'shin, Y. Kawakubo, M. Moriyama, Y. Yamada, A. Tezuka, S. Matsukawa (AGU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), I. Takahashi (IPMU), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena) and the CALET collaboration: The long, bright GRB 180305A (Fermi-LAT detection: Axelsson & Bissaldi, GCN circ. 22457; Fermi-GBM detection: Veres & von Kienlin, GCN circ. 22458; Konus-Wind detection: Svinkin et al., GCN circ. 22461) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 09:26:09.218 UTC on 5 March 2018. No real time CGBM GCN notice was distributed about this trigger because the real time communication from the ISS was off (loss of signal) between 9:00 and 9:36. The burst signal was seen by all CGBM detectors. The burst light curve shows a single multi-peaked pulse which starts at T-0.5 sec, peaks at T+3.4 sec and ends at T+14.6 sec. The T90 and the T50 durations measured by the SGM data are 10.0 +- 0.8 sec and 3.88 +- 0.13 sec (40-1000 keV), respectively. CGBM HV was turned off at ~T+95 sec due to entering the radiation belts, so no CGBM data are available from that time until ~T+1300 sec. The ground processed light curve is available at http://cgbm.calet.jp/cgbm_trigger/ground/1204276876/ On March 2, the CGBM on-board event data capture end time was changed from 8 sec to 512 sec, so from that time in the Event mode CGBM collects time tagged events up to T0+512 sec, where T0 is the trigger time. The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University.