TITLE: GCN CIRCULAR NUMBER: 20783 SUBJECT: LIGO/Virgo G275697: CALET Observations DATE: 17/03/01 08:46:12 GMT FROM: Takanori Sakamoto at Aoyama Gakuin U Y. Yamada, A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), 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 CALET Gamma-ray Burst Monitor (CGBM) was operating at the trigger time of G275697 (GCN Circ. 20763). No CGBM on-board trigger occurred at the time of the event. Based on the LIGO localization sky map (bayestar.fits.gz), the part of the northern arc of the high probability area was in the field-of-view of CGBM. The summed LIGO probabilities inside the HXM and the SGM field of view are 32% and 70%. Based on the analysis of the light curve data with 0.125 sec time resolution from -60 sec to 60 sec from the trigger time, we found no significant excess around the trigger time in either the HXM (7-3000 keV) or the SGM (40 keV -28 MeV) data. The CALET Calorimeter (CAL) was operating in high energy trigger mode at the trigger time of G275697. However, no LIGO high probability region was included in the CAL's field of view at the time of the trigger.