GCN Circular 25537
Subject
LIGO/Virgo S190828l: No transient candidates in CALET observations
Date
2019-08-29T04:17:41Z (5 years ago)
From
Yuta Kawakubo at Louisiana State U./CALET <kawakubo1@lsu.edu>
Y. Shimizu (Kanagawa U), 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),
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 S190828l T0 = 2019-08-28 06:55:09.887 UT (The LIGO
Scientific Collaboration and Virgo Collaboration, GCN Circ. 25503).
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 5 % and 41 %, respectively (and 79 % credible region
of the initial localization map was above the horizon). The HXM and
SGM fields of view were centered at RA = 109.4 deg, Dec = 60.9 deg
and RA = 107.0 deg, Dec = 51.0 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 S190828l, but the CAL FOV
does not have any overlap with the high probability localization region.
The CAL FOV was centered at RA = 106.9 deg, DEC = 51.0 deg at T0.