[vsnet-grb-info 25131] LIGO/Virgo S200224ca: Upper limits from CALET observations.

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  27231
SUBJECT: LIGO/Virgo S200224ca: Upper limits from CALET observations.
DATE:    20/02/27 05:53:24 GMT
FROM:    Yuta Kawakubo at Louisiana State U./CALET  <kawakubo1 at lsu.edu>

Y. Kawakubo (LSU), A. Yoshida, T. Sakamoto, V. Pal'shin,
S. Sugita (AGU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
Y. Asaoka, 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 
S200224ca T0 = 2020-02-24 22:22:34.406 UT (The LIGO 
Scientific Collaboration and Virgo Collaboration, GCN 
Circ. 27184), the CALET Gamma-ray Burst Monitor (CGBM)
high voltages were off (from T0-18 min to T0+1 min).

The CALET Calorimeter (CAL) was operating in the high 
energy trigger mode at the trigger time of S200224ca. 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 in the overwrap region with the
LIGO-Virgo high probability localization region.  The 90% 
upper limit of CAL is 5.0 x 10^-7 erg/cm^2/s (10-100 GeV) 
when the summed LIGO-Virgo probability reaches 95%. The CAL 
FOV was centered at RA = 167.5 deg, DEC = -24.8 deg at T0.