TITLE: GCN CIRCULAR NUMBER: 33897 SUBJECT: LIGO/Virgo/KAGRA S230529ay: Upper limits from CALET observations. DATE: 23/05/30 19:42:13 GMT FROM: Yuta Kawakubo at Louisiana State University kawakubo1@lsu.edu
S. Sugita, A. Yoshida, T. Sakamoto (AGU), Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (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 S230529ay T0 = 2023-05-29 18:15:00 UT (The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration, GCN Circ. 33889, 33891) the CALET Gamma-ray Burst Monitor (CGBM) high voltages were off (from T0-2 min to T0+3 min).
The CALET Calorimeter (CAL) was operating in the high energy trigger mode at the trigger time of S230529ay. Using the CAL data, we 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 LVK high probability localization region. The 90% upper limit of CAL is 1.2 x 10^-5 erg/cm^2/s (10-100 GeV) when the summed LVK probability reaches 20%. The CAL FOV was centered at RA = 118 deg, DEC = +47 deg at T0.
The preliminary CGBM analysis for O4 events can be found here: http://cgbm.calet.jp/cgbm_trigger/O4