TITLE:   GCN CIRCULAR
NUMBER:  21668
SUBJECT: LIGO/Virgo G298389: CALET Observations
DATE:    17/08/24 00:03:32 GMT
FROM:    Takanori Sakamoto at Aoyama Gakuin U  <tsakamoto@phys.aoyama.ac.jp>

I. Takahashi (IPMU), A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama,
Y. Yamada, A. Tezuka, S. Matsukawa (AGU), K. Yamaoka (Nagoya U),
S. Nakahira (RIKEN), 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), A. V. Penacchioni, P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The CALET Gamma-ray Burst Monitor (CGBM) was operating at the trigger time
of G298389 (The LIGO Scientific Collaboration and Virgo Collaboration,
GCN Circ. 21600).  No CGBM on-board trigger occurred at the time
of the event.  Based on the LIGO localization sky map (LIB.fits.gz),
none of the probability area was in the field-of-view of the CGBM/HXM.
However, 13.4% of the summed probability was inside the field-of-view
of the CGBM/SGM.

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 low energy trigger mode at the
trigger time of G298389.  However, no LIGO high probability region was included
in the CAL's field of view at the time of the trigger.