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GCN Circular 35115

GRB 231115A: Upper limit from CALET Gamma-Ray Burst Monitor
2023-11-19T05:41:13Z (6 months ago)
Yuta Kawakubo at Louisiana State University <>
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Y. Kawakubo (LSU), A. Yoshida, T. Sakamoto, S. Sugita (AGU),
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:

The CALET Gamma-ray Burst Monitor (CGBM) was operating at
the trigger time of the short GRB 231115A
T0 = 2023-11-15 15:36:21.20 UT (Fermi GCN: #35035, #35044;
Integral GCN: #35037; Glowbug GCN #35045; Insight-HXMT/HE GCN
#35060; Konus-Wind GCN #35062; Swift-BAT GCN #35065).

No CGBM onboard trigger occurred around T0. Based on the IBAS
localization, the incident angles to HXM and SGM are 79 degrees and
85 degrees, respectively (#35037). Based on the analysis of the light
curve data with 0.125 sec time resolution, we found a hint of the burst
emission around the trigger time in HXM2 and SGM data.  However, the
significance of 4.8 (HXM2) and 4.7 (SGM) sigma is below our detection
criterion to the CGBM data.

The five sigma upper limit of SGM for a 0.125 integration time is
3.0e-6 erg/cm^2/s (10 - 1000 keV), assuming a power-law with
an exponential cutoff (alpha = 0.5, Epeak = 580 keV, reference to
#35044) and the IBAS position.

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.
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