[vsnet-grb-info 22518] No transient candidates from CALET observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  24617
SUBJECT: No transient candidates from CALET observations
DATE:    19/05/21 03:22:54 GMT
FROM:    Yuta Kawakubo at Louisiana State U./CALET  <kawakubo1 at lsu.edu>

S. Nakahira (RIKEN),  A. Yoshida, T. Sakamoto, V. Pal'shin, 
S. Sugita (AGU), Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), 
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 S190519bj T0 = 2019-05-19 15:35:44.398  UT (The 
LIGO Scientific Collaboration and Virgo Collaboration, GCN Circ. 
24598). 
 
No CGBM on-board trigger occurred around the event time.  Based
on the LIGO-Virgo localization sky map, most of the high  probability
area was within the field-of-view of the CGBM SGM.  The summed 
LIGO probabilities inside the CGBM HXM (7-3000 keV) and SGM 
(40 keV - 28 MeV)  fields of view are 32% and 87%, respectively 
(and 100% credible region of the initial localization map was above
the horizon).  The HXM and SGM fields of view were centered at 
RA = 244.6 deg, Dec = 61.1 deg and  RA = 243.1 deg, Dec = 51.1 deg 
at T0, respectively.

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 (signal-to-noise ratio >= 7) around the trigger 
time in either the HXM or the SGM data. 

The CALET Calorimeter (CAL) was operating in the high energy
trigger mode at the trigger time of S190519bj. 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=243.1 deg, Dec=51.1 deg at T0.