TITLE: GCN CIRCULAR NUMBER: 24495 SUBJECT: LIGO/Virgo S190510g: CALET Observations DATE: 19/05/12 03:01:00 GMT FROM: Yuta Kawakubo at Louisiana State U./CALET P. S. Marrocchesi (U of Siena), A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU), Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC), M. L. Cherry (LSU), S. Ricciarini (U of Florence), and the CALET collaboration: The CALET Gamma-ray Burst Monitor (CGBM) was operating at the trigger time of S190510g T0=2019/05/10 02:59:39.292 UT (The LIGO Scientific Collaboration and Virgo Collaboration, GCN Circ. 24442, 24448 and 24462). No CGBM on-board trigger occurred around the event time. Based on the LIGO-Virgo localization sky map, most of the part of the high probability area was outside of the field-of-view of CGBM. The summed LIGO probabilities inside the HXM and the SGM field of view are 2% and 7% (and 84% credible region of the updated localization map were Earth-occulted). The HXM and SGM field of views were centered at RA=298.7 deg, Dec = 60.7 deg and RA=295.7 deg, Dec=50.8 deg at T0. Based on the analysis of the light curve data with 0.125 sec time resolution from T0-60 sec to T0+60 sec, 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 S190510g. Using CAL data, we have searched for gamma-ray events in the 10-100 GeV band from -60 sec to +60 sec from the GW trigger time and found no candidates. There is no significant overlap with the LVC location probability map. The CAL FOV was centered at RA=295.7 deg, Dec=50.8 deg at T0.