[vsnet-grb-info 23035] LIGO/Virgo S190720a: Upper limits from CALET observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  25134
SUBJECT: LIGO/Virgo S190720a: Upper limits from CALET observations
DATE:    19/07/21 04:41:47 GMT
FROM:    Yuta Kawakubo at Louisiana State U./CALET  <kawakubo1 at lsu.edu>

S. Sugita, A. Yoshida, T. Sakamoto, V. Pal'shin (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:

At the trigger time of the compact binary merger candidate S190720a,
T0 = 2019-07-20 00:08:36.704 UT (The LIGO Scientific Collaboration 
and Virgo Collaboration, GCN Circ. 25115), the CALET Gamma-ray 
Burst Monitor (CGBM) high voltages were off (from T0-4 min to 
T0+17 min).

The CALET Calorimeter (CAL) was operating in the high energy
trigger mode at the trigger time of S190720a. Using the 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 3.0x10^-5 erg/cm^2/s (10-100 GeV) when
the summed LIGO-Virgo probability reaches 25%.
The CAL FOV was centered at RA = 49.7 deg and DEC = -32.1 deg at T0.