[vsnet-grb-info 23636] LIGO/Virgo S190910h: Upper limits from CALET observations.

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  25735
SUBJECT: LIGO/Virgo S190910h: Upper limits from CALET observations.
DATE:    19/09/13 03:38:21 GMT
FROM:    Yuta Kawakubo at Louisiana State U./CALET  <kawakubo1 at lsu.edu>

M. L. Cherry (LSU), A. Yoshida, T. Sakamoto, V. Pal'shin,
S. Sugita (AGU), Y. Kawakubo (LSU), K. Yamaoka (Nagoya U),
S. Nakahira (RIKEN), Y. Asaoka, S. Torii (Waseda U), Y. Shimizu, 
T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC), 
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 S190910h T0 = 2019-09-10 08:29:58.544 UT (The LIGO Scientific
Collaboration and Virgo Collaboration, GCN Circ. 25707).

No CGBM on-board trigger occurred around the event time.  Based
on the LIGO-Virgo localization sky map, the summed LIGO probabilities 
inside the CGBM HXM (7 - 3000 keV) and SGM (40 keV - 28 MeV) fields 
of view are 16 % and 50 %, respectively (and 75 % credible region 
of the initial localization map was above the horizon).  The HXM and 
SGM fields of view were centered at RA = 286.6 deg, Dec = 0.3 deg
and RA = 294.8 deg, Dec = -5.4 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 around the trigger
time in either the HXM or the SGM data.

The CALET Calorimeter (CAL) was operating in the low energy trigger
mode at the trigger time of S190910h. Using the CAL data, we have 
searched for gamma-ray events in the 1-10 GeV band from -60 sec 
to +60 sec from the GW trigger time and found no candidates 
in the overlap region with the LIGO-Virgo high probability localization
region. The 90% upper limit of CAL is 9.4x10^-6 erg/cm^2/s (1-10 GeV)
when the summed LIGO-Virgo probability reaches 10%.  The CAL FOV 
was centered at RA= 294.8 deg, DEC= -5.5 deg at T0.