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GCN Circular 24531

LIGO/Virgo S190512at: CALET Observations
2019-05-14T03:46:33Z (5 years ago)
Yuta Kawakubo at Louisiana State U./CALET <>
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),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The CALET Gamma-ray Burst Monitor (CGBM) was operating at the 
trigger time of S190512at T0=2019-05-12 18:07:14.422UT (The LIGO 
Scientific Collaboration and Virgo Collaboration, GCN Circ. 24503). 

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 inside of the field-of-view of SGM.  The 
summed LIGO probabilities inside the HXM and the SGM field of
view are 19% and 95% (and 0% credible region of the initial
localization map were Earth-occulted).  The HXM and SGM field of
views were centered at RA=205.5 deg, Dec = 44.8 deg and
RA=214.9 deg, Dec=37.7 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 S190512at. 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.
The 90% upper limit of CAL is 1.9x10^-5 erg/cm2/s (10-100 GeV) when
the summed LIGO-Virgo probability reaches 10%.
The CAL FOV was centered at RA=214.9 deg, Dec=37.7 deg at T0.
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